I had the same problem and asked it a few months ago (I will search the post).
The A&H App does not support the authorization concept from the console.
So the user will always be admin.
If your musician use ipads for the in-ear mixing, I would recommend you to use the GLD One-Mix App instead of the GLD remote.
The A&H Apps are in my opinion really bad (compared to Behringer X32).
With the GLD One-Mix you will need 1 iPad per Mix (In-Ear Channel).
Seems like the A&H guys never use their one gear in real live.
I can’t imagine to have 8 iPads on the stage.
I think it would be easier to change the mixing channel in the app and use one iPad for every AUX channel.
Maybe the A&H guys use 8 monitor mixing consoles for 8 Aux channels…