This code isn't working for no apparent reason.
No errors, no output. The code is in a LocalScript inside the TextButton.
local playButton = script.Parent -- "script.Parent" is a TextButton
playButton.MouseButton1Click:Connect(function()
print("Clicked.")
end)

2 comments
What script do you used? Script or LocalScript?
If you used script, copy all this code and paste it in local