Answer
On Apps10, Lobby editing (data sources, elements, and the rest of the setup) still has to be done in IEE — Aurena on Apps10 only displays the Lobby overview, without the editing capability that was later added to Aurena in Cloud. If your users need to edit Lobbies themselves rather than just view them, they'll need IEE access on Apps10, even if their day-to-day work is otherwise entirely in Aurena.