Error joining Arma 3?

See if this helps you:

https://www.exilemod.com/topic/17410-steam-authentication-failed/

Navigate to your Steam folder and locate a file called “steam_appid.txt” in there you will find a short 6 decimal ID copy that.

Then navigate to @ExileServer folder and open the “Config.cfg” file with an editor of your choice( I used notepad++). Look for the line that says “requiredBuild = ” change that id number with the one you copied and save.

Then navigate back to your base server folder and locate “steam_appid.txt”, the same file that is in your base Steam is in the base server folder open it and replace the id with the copied ID and then save.

Launch the server and you should be good to go.