Adding admins to your server is quite simple. The system acts as a whitelist that works off of Steam64 IDs. You can obtain the ID for a player using this tool here. 

Step 1: Log into our game panel

Step 2: Open your File Manager

Step 3: Create a file called AllowedCheaterSteamIDs.txt in the directory ShooterGame\Saved

Step 4: Enter each Steam ID (remember, Steam64 ID) on each line. For instance, if you had 3 admins, you'd add them like this:

ID1GoesHere

ID2GoesHere

ID3GoesHere