You can add admins in Advanced Mode.
All you need is the
Alderon Games ID of the respective player.
Open the Game.ini and scroll to
Add the desired players below. The whole thing would look like this:
[/Script/PathOfTitans.IGameSession] ServerAdmins=048-236-424 ;I am a comment ServerAdmins=123-456-789 ServerAdmins=543-226-532
Only one admin can be added per line.
An overview of the available commands can be found here: Admincommands.