Why doesn't my Animation play when I hit the specific hotkey? (Answered!)

Alright, so I have spotted two issues with the script.

On line 5, you are calling Key to be equal to 'e'. However, as far as I'm aware, UIS keycodes go by the capital letter, so just make a mental note to be aware of that.

As well as that, on line 8, the formatting for the animation is incorrect. Roblox's format this is rbxassetid://[InsertCodeHere]. So it should be replaced with rbxassetid://2456539535.

local UIS = game:GetService('UserInputService')
local plr = game.Players.LocalPlayer
local Char = plr.Character or plr.CharacterAdded:wait()

local Key = 'E' --Make sure to capitalize it!

local animation = Instance.new("Animation")
animation.AnimationID = 'rbxassetid://2456539535' --The is the appropriate format

local Debounce = true

UIS.InputBegan:Connect(function(Input, IsTyping)
 if IsTyping then return end
 local KeyPressed = Input.KeyCode
 if KeyPressed == Enum.KeyCode[Key]and debounce then
    Debounce = false
    local LoadAnimation =Char.Humanoid:LoadAnimation(Animation)
    LoadAnimation:Play()
    wait(2)
    Debounce = true
 end
end)

All in all, just make sure you have that E capitalized and have the right format for animations. (That format is the same for decals, images, etc.)