Making a only group member gui script

I suggest you read up on this more

Exploiters can change the Visible property on their client, giving them complete access to GUI they have no right in being in.

Instead, I suggest you use this instead

game.Players.PlayerAdded:Connect(function(Player)
	if Player:IsInGroup(ID) then
		local UIClone = game.ServerStorage.AdminGui:Clone()
		UIClone.Parent = Player.PlayerGui
		UIClone.ResetOnSpawn = false
	end
end)

Use a ServerScript and have it check for who joins the server, check if they’re in the server, and clone a UI from ServerStorage or anywhere else the player cannot see (exploiters cannot see ServerScriptService and ServerStorage primarily), its important that the client cant see the source Gui so any exploiter cant just copy it over to their playergui and use it to their hearts content

The only downside to having this Severside is that the information is not live (if they leave the group while being in the game, the game will think they’re still in the group until they leave), but i doubt thats of much concern in this usecase