How to clone player character when joined?

If I recall correctly, the player's Character has Archivable set to false, meaning you cannot clone it. All you really have to do is set this value to true, and you will be able to clone the player's Character.

However, if the Character respawns, you'll need to do it again, thus considering the use of CharacterAdded:

player.CharacterAdded:Connect(function(character)
	character.Archivable = true
	print(character.Archivable) -- verify that the value was changed
end)

If this fails to work you'll need to use the literal model in the Workspace whose name is the name of the player.