PhanZero: Can't install it too... stops at 2% before loading anything with error E3 (according to help that is an error on my side, firewall or antivirus), when trying to get offline installer the JSON response says I don't have a valid license. So something's really broken with the game, the servers or whatever. Never had these issues with a game here, so I guess they'll fix it, just sad I can't play it now...
//edit Seems to load now... slowly, but it loads...
I had this problem too today, i tried everything but no change, i just restart my PC and i'm now i just finished downloading and it's installed.
It also inported my cloud saves and setting from my Steam Cloud...i didn't expect that until i realised i still have old files from my previous playthrough.
Anyway it's running fine, for now.