How come my keybinds wont work for my r15 shield script?

So I have a shield script that I modified to work in r15, but since I don't know much about hot keybinds work I thought it would be fine if I did not change them, but since they don't work I'm looking for plenty of help on how keybinds work and how I could fix the keybind issue.

-------------[|Script|]----------------

wait(.1)

Player = game.Players.LocalPlayer
Character = Player.Character
LeftHand = Character:FindFirstChild("LeftHand")
UpperTorso = Character:FindFirstChild("UpperTorso")
UpperLeftArm = UpperTorso:FindFirstChild("UpperLeftArm")

ShieldTemplate = script:WaitForChild("ShieldTemplate")
VariantShield = script:WaitForChild("VariantShield")
RemoveFunction = script:WaitForChild("RemoveShield")

Use = false
DataY = 0
Up = false
Down = false
Busy = false
AnimationSpeed = 10 -- Slower, smoother with more integers

ShieldLink = nil
Weld = nil
LeftShoulderMotor = nil

local function WeldDecoration(Variant, WeldTo)
	local g = Variant:Clone()
	g.Parent = WeldTo.Parent
	local C = g:GetChildren()
	for i = 1, #C do
		if C[i]:IsA("BasePart") then
			C[i].CanCollide = true
			local W = Instance.new("Weld")
			W.Part0 = g.Middle
			W.Part1 = C[i]
			local CJ = CFrame.new(g.Middle.Position)
			local C0 = g.Middle.CFrame:inverse()*CJ
			local C1 = C[i].CFrame:inverse()*CJ
			W.C0 = C0
			W.C1 = C1
			W.Parent = g.Middle
		end
		
		local Y = Instance.new("Weld")
		Y.Part0 = WeldTo
		Y.Part1 = g.Middle
		Y.C0 = CFrame.new(0, 0, 0)
		Y.Parent = Y.Part0
	end

	local h = g:GetChildren()
	for i = 1, # h do
		h[i].Anchored = false
		h[i].CanCollide = false
	end
end

local function CreateShield()
	local Shield = ShieldTemplate:Clone()
	Shield.Name = "Shield"
	Shield.Parent = Character
	WeldDecoration(VariantShield, Shield.Handle)
	Shield:MoveTo(Character.UpperTorso.Position)
	ShieldWeld = Instance.new("Weld", Shield)
	ShieldWeld.Part0 = LeftHand
	ShieldWeld.Part1 = Shield.Handle
	
	local ShieldTag = Instance.new("StringValue", Shield.Handle)
	ShieldTag.Name = "IsShield"
	ShieldTag.Value = "Wood"
	
	ShieldWeld.C0 = CFrame.new(-0.175, -0.1, 0) * CFrame.fromEulerAnglesXYZ(math.rad(90),math.rad(90), 0)
	ShieldLink = Shield
end

function CommandIssued(Type, Data)
	if Type == "KeyPress" and Data ~= nil then
		local Key = Data:lower()
		if Key == "r" then
			if not Use and not Busy then
				Busy = true
				if not Character:FindFirstChild("Shield") then
					CreateShield()
				end
				LeftShoulderMotor = UpperTorso["UpperLeftArm"].C1 -- Save data
				UpperLeftArm.Part1 = nil -- Disconnect arm from shoulder
				Weld = Instance.new("Weld") -- New Weld LeftArm to Torso
				Weld.Name = "LeftHand Weld"
				Weld.Part0 = UpperTorso
				Weld.Part1 = LeftHand
				Weld.Parent = UpperTorso
				Weld.C0 = CFrame.new(-1.5,0,0) -- Reposition arm
				
				for i = 1,AnimationSpeed do
					Weld.C0 = Weld.C0 * CFrame.new(0.5/AnimationSpeed,-0.25/AnimationSpeed,-1/AnimationSpeed)*CFrame.fromEulerAnglesXYZ(math.rad(70/AnimationSpeed),math.rad(-40/AnimationSpeed),math.rad(40/AnimationSpeed)) -- if you tweak the numbers long enough you manage to get a smooth animation, sometimes it takes really long until you finally get all the positions right but when it comes to cframe/Weld manipulation the best way to achieve the wanted formula is trough trial and error
					wait()
				end
				
				Busy = false
				Use = true
			else
				if not Busy then
					Busy = true
					if DataY > 0 then
						for i = 1, DataY do
							DataY = DataY - 1
							Weld.C0 = Weld.C0 * CFrame.new(0,0,0.04)*CFrame.fromEulerAnglesXYZ(math.rad(-3),math.rad(1),math.rad(0))
							if ShieldWeld ~= nil then
								ShieldWeld.C0 = ShieldWeld.C0 * CFrame.new(.02, 0, .015) * CFrame.fromEulerAnglesXYZ(math.rad(.9), math.rad(-2), math.rad(.75)) -- SHIELD WELD HERE
							end
							wait()
						end
					end
					for i = 1, AnimationSpeed do
						Weld.C0 = Weld.C0*CFrame.new(-0.5/AnimationSpeed,0.25/AnimationSpeed,1/AnimationSpeed)*CFrame.fromEulerAnglesXYZ(math.rad(-70/AnimationSpeed),math.rad(40/AnimationSpeed),math.rad(-40/AnimationSpeed)) -- the equiping animation reversed
						wait()
					end
					ShieldWeld.C0 = CFrame.new(-0.175, -0.1, 0) * CFrame.fromEulerAnglesXYZ(math.rad(90),math.rad(90), 0)
					Weld:Destroy()
					UpperLeftArm.Part1 = LeftHand
					UpperLeftArm.C1 = LeftShoulderMotor
					DataY = 0
					Use = false
					Busy = false
				end	
			end
		elseif Key == "r" then
			if Up == false and Down == false and Use == true and Busy == false then
				Up = true
				while Up == true and DataY < 30 do
					DataY = DataY + 1
					Weld.C0 = Weld.C0 * CFrame.new(0, 0, -0.04) * CFrame.fromEulerAnglesXYZ(math.rad(3),math.rad(-1),math.rad(0))
					if ShieldWeld ~= nil then
						ShieldWeld.C0 = ShieldWeld.C0 * CFrame.new(-.02, 0, -.015) * CFrame.fromEulerAnglesXYZ(math.rad(-.9), math.rad(2), math.rad(-.75)) -- SHIELD WELD HERE
					end
					wait()
				end	
			end
		elseif Key == "t" then
			if Down == false and Up == false and Use == true and Busy == false then
				Down = true
				while Down == true and DataY > 0 do
					DataY = DataY-1
					Weld.C0 = Weld.C0 * CFrame.new(0, 0, 0.04) * CFrame.fromEulerAnglesXYZ(math.rad(-3),math.rad(1),math.rad(0))
					if ShieldWeld ~= nil then
						ShieldWeld.C0 = ShieldWeld.C0 * CFrame.new(.02, 0, .015) * CFrame.fromEulerAnglesXYZ(math.rad(.9), math.rad(-2), math.rad(.75)) -- SHIELD WELD HERE
					end
					wait()
				end	
			end
		end
	elseif Type == "Remove" then
		if Weld then
			Weld:Destroy()
		end
		UpperLeftArm.Part1 = LeftHand
		if ShieldLink then
			ShieldLink:Destroy()
		end
	end
end

function CommandStopped(Key)
	Key = Key:lower()
	if Key == "i" then
		Up = false
	elseif Key == "u" then
		Down = false
	end
end

function RemoveFunction.OnClientInvoke()
	CommandIssued("Remove")
end

CreateShield()

Player:GetMouse().KeyDown:connect(function(Key)
	CommandIssued("KeyPress", Key)
end)

Player:GetMouse().KeyUp:connect(CommandStopped)

----[|Scripts Children|]----

A remote function named "RemoveShield" A model named "ShieldTemplate" A model named "VariantShield"

Assuming you have a local script under the tool, you can get the players mouse like this:

--Local script under the tool
local player = game:GetService('Players').LocalPlayer -- Gets the player
local mouse = player:GetMouse() -- Gets mouse

script.Parent.Equipped:connect(function()
mouse.KeyDown:connect(function(Key)
	if Key == 'r' then -- If the key is r then
		Key:lower()
		print('key')
		script.Parent.Handle.BrickColor = BrickColor.Random() -- The handle will change color
	end
end)
end)

I hope this example helps you. If not please notify me.

Edit: I made some modifications to the script so it can have a forcefield function when a player presses the key 'R' so you can get a better understanding(just in case)

local player = game:GetService('Players').LocalPlayer
local mouse = player:GetMouse()

script.Parent.Equipped:connect(function()
mouse.KeyDown:connect(function(Key)
	if Key == 'r' then
		Key:lower()
		print('key')
		script.Parent.Handle.BrickColor = BrickColor.Random() --Handle changes color
		local shield = Instance.new('ForceField') --Makes a new instance, which is a forcefield
		shield.Name = 'Shield'
		shield:Clone().Parent = player.Character --We clone the shield into the players character for protection
		mouse.KeyUp:connect(function(Key) --function is called when the player lets the key up
			if Key == 'r' then --if the key they let go is R then
				Key:lower()
				local sh = player.Character:WaitForChild('Shield')
				sh:Destroy() --Shield is destroyed
			end
		end)
	end
end)
end)