He’s got a BattleEye issue. So its not something Funcom can handle. Especially since he is renting a server.
Its probably some issue with it being turned off or corrupted on his end and the server isn’t able to sync it. Its uncommon but sometimes Steam doesn’t install BattleEye properly. And the process for it I don’t believe is as simple as reinstalling it.
In your server settings via the host you should have an option to turn it off. If you’re running the steam version of the game you should be able to launch Conan Exiles without BattleEye. If that option isn’t popping up (if you clicked don’t show again) you should be able to uninstall it through windows. I’m not exactly sure how to do that since I’ve not installed it with Conan in quite a few years.