i tried everything.
Try running either steam or the game as admin. I've found some EAC games need steam ran with admin priviliges to actually work properly.
same problem runing steam as admin, and this problem runing the game as admin:
Ok, so I had this one... you're one step further, so that's good.
What I had to do was reboot my PC and then run the game. Then windows firewall popped up, asked for permission for DbD, so I clicked accept and then it worked.
So I'd try that. I'd also check any other firewall programs you have running.