I saw a thread with ppl asking bout the same problem but no one answered.
I'd saw that it probably has something to do with MEGA, they fit the bill of being the "third party website", since u install the game from the mega website.
I dont know how to fix it, maybe trying to download the game not through MEGA(I dont think there is a link that is not MEGA) or try to install the MEGA app on your pc and see if that makes it compatible..