textbutton isnt appearing in roblox studio game thing but is when i press stop?

Ahh, I see. From your video, I can see that you're getting the Shop button by StarterGui. Always remember that you can't get a button from the StarterGui when the game starts. It's because when the game starts StarterGui will be moved to the client player and be renamed to "PlayerGui". Instead, you can get the "MenuGui" by playBtn.Parent.Parent:WaitForChild("Shop").

Why use WaitForChild? You must always use WaitForChild in a client script because most of the time the client loads faster than the server, and the server provides all Instances of the game, including GUIs. WaitForChild waits until a specific child has been found, and will return that child.

local camera = workspace.CurrentCamera
local playBtn = script.Parent
local gamelogo = script.Parent.Parent:WaitForChild("GameLogo")
local shop = playBtn.Parent.Parent:WaitForChild("Shop")

repeat
	task.wait(.1)
	camera.CameraType = Enum.CameraType.Scriptable
until camera.CameraType == Enum.CameraType.Scriptable

camera.CFrame = workspace:WaitForChild("MenuCamera").CFrame

local function onPlay()
	camera.CameraType = Enum.CameraType.Custom
	playBtn.Visible = false
	workspace:WaitForChild("MenuCamera"):Destroy()
	gamelogo:WaitForChild("A"):Destroy()
	gamelogo:WaitForChild("F"):Destroy()
	gamelogo:WaitForChild("K"):Destroy()
	shop.Visible = true
end

playBtn.Activated:Connect(onPlay)