Originally Posted by DLHubber

You just need to scan your passport via the app or a kiosk, like it says. The app has never worked properly for me, but once I scanned it at a kiosk I've been good.

And yes, it has to be scanned either in the app or at a kiosk. Scanning it when you check your bags or at the gate will not verify your passport in your profile, just for that flight.