Black Ops 6 not loading on Steam?

Hey, I bought BO6 yesterday on Steam for 80 euros and somehow I want to start the game and on the left it says it is running but then 1-2 seconds later it says "Start game" again because a few other people have the problem. Unfortunately, I haven't found a solution yet. I've tried everything for hours without success. The game freezes almost immediately as soon as I start it and it crashes immediately after starting. I've tried everything.