ArditBauMalKopf I'm out of ideas then. You could try changing DNS to 1.1.1.1 or try a VPN, but doubt they'd work since that error's related to somehow running older versions of Plutonium hence its failing to authenticate.
Vany_Trip Follow this guide to repair your game files, and please don't hijack threads, this thread has nothing to do with your error - if you encounter any more issues create your own thread.