Im new to coding so please don't judge. The code i wrote in the part is :
script.Parent.ClickDetector.MouseClick:connect(function(player) player.PlayerGui.ObbyGui.Enabled = true end)
The name of the screen gui is ObbyGui btw. This was wrote in a local script in workspace.
You just made a few mistakes to the script Here is the correct version
script.Parent.ClickDetector.MouseClick:Connect(function() -- "connect" is old and you shouldn't insert "player" into the function player.PlayerGui.ObbyGui.Enabled = true end)