I have found the solution to this problem but i do not know if it will work for you but this is how i got my game to work. 1. Go to your steam games and right click rust and go to properties.
2.Go to Betas and go to None and let your game update.
3.Run rust like normal and let EasyAntiCheat install you might get another Error that say game error code 5 DON’T worry i will show how to get rid of that.
4.Close steam completely
5.Right click your steam.exe and run it as administrator
6.Now run rust you should be able to play