If you don't have a mobile data plan, it will affect your ability to download the ticket and QR code. Instead, you can screenshot or add your ticket to Wallet (iPhones only). When you have access to wifi you can view your ticket in the Atom app. First tap the menu in the top left, next tap "My Tickets & Rallies" where you can view your upcoming movie and corresponding QR code. Add the ticket to your passbook by tapping "Add to Apple Wallet". Or take a screenshot of the QR code to save the image on your phone. You can now have your ticket available for scanning at the theater.