Several recent posts got to websites wanting $65 to file the app. Those websites are a scam.
The easiest way to avoid bring ripped off is to go to the Goggle or Apple store and download the app. It is free!!!! No cost. Gratis.
Suggest using a phone as taking a picture of yourself, covid card and passport are automatically formatted by cell phones.
If you do not complete the app you are not allowed to board, thus boarding gets slowed. Proof either by printed copy or showing your phone. It only takes a few minutes if you have your passport and covid cards handy.