I was started the realistic ground battle normal and I have this error
You need to fix EAC…
Firstly, you want to check the launcher if you use the gaijin launcher, and just above the play button is an EAC option, that should be on.
If that doesn’t fix it, then you either need to make the exception in your antivirus for the game folder, or run the EAC setup in the EAC folder in the game folder as administrator, and repair service.