Hint: before you do the following things just take a look into that FAQ article: https://avmg.eu/index.php?faq-…els-verbessern/
Deleting BattlEye
This error occurs when the game is not able to contact with the servers BattlEye service or with the BattlEye servers.
Check in Task Manager if this process is running and kill it with right click:
Go in these folders and check for BattlEye folders and delete them:
After that, please restart your Computer so running processes are closed. When done, please verfiy the game cache via Steam:
After that, start Arma 3 and check out under BattlEye if the setting is correctly set:
Above didn't helped?
If you already did the above mentioned multiple times you can also do the following:
Go to %userprofile%\Appdata\Local\Arma 3 and delete the files in that folder. You can download the following file to manage to find the folder easier: https://sys.avmg.eu/public/dl/arma3/arma3-rpt-folder.zip - this is a Batch file. Just run it and delete every item inside that folder.
If that also doesn't help you might running a outdated system. If you have a Laptop, don't bother trying. If your computer is running a HDD and you have Arma 3 installed on that drive, move Arma 3 to a SSD, better NVMe drive.