- First you will need to make sure your server is stopped before updating the config file
- Click the quick edit tab 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
- Underneath that heading you will see a line "ServerPassword="
- Enter a password, save the file and restart your server
A more comprehensive guide can be found here - http://18.104.22.168/Community_Servers