1. If you are using Arma 3 Launcher, then it's probably already enabled, but if not, just:
- go to Options
- tick the "Use Battleye" checkbox
2. If you use any shortcut, PWS or other Launcher program, you will have to tell it to not run arma3.exe anymore, but instead run arma3battleye.exe with some parameters.
So change:
to"c:\Program Files\Steam\SteamApps\common\Arma 3\arma3.exe" -noSplash -skipIntro -noFilePatching -showScriptErrors -mod=@CBA_A3;@TacBF;...
"c:\Program Files\Steam\SteamApps\common\Arma 3\arma3battleye.exe" 0 1 -noSplash -skipIntro -noFilePatching -showScriptErrors -mod=@CBA_A3;@TacBF;...
Admins: after 7 days, move topic to Technical Support forum.