- First you will need to make sure your server is stopped before updating the config file
- Grab the admins Steam 64 ID using https://steamid.io/
- Click the quick edit tab in the game panel and edit DefaultGame.ini by using the button on the left hand side of the file name
- Look for [/Script/ShooterGame.BattalionGameMode] in the file
- Add the admin on a new line below [/Script/ShooterGame.BattalionGameMode] using +AdminSteamIDs="xxxxxxxxx" where x is the admins steam id 64
- Restart your server and you're done !
A more comprehensive guide can be found here - http://126.96.36.199/Community_Servers