score:5
The app is sufficient. You just go straight to security and scan your QR code there. If you're worried about running out of battery on your phone, you can print a boarding pass in one of the self check-in machines to have as a backup. Good luck on your first flight!
Upvote:2
The QR code should be enough. However, make sure your device has sufficient battery charge left to last until after you board the plane (for that reason alone, I nearly always print a physical copy as well).