I purchased The game and most of the expansions on Steam. Then I recently found out there is a mobile app for iOS. I looked at and followed the directions on https://forums.obsidian.net/topic/92893-how-to-merging-desktop-and-mobile-accounts/. After entering in the PFID and the Secret Key, the iOS app is locked on the screen saying Processing... definitely waited for 5+ minutes several times and I made sure to get a new Secret Key each time.
My PFID is 419D4B760BF4248D