I just did the digital document check-in and it was a breeze. Submitted my documents yesterday afternoon, immediately got a reply that the documents had been successful uploaded, and this morning, about 2:00 am, I got another email stating they had been approved.
I used the website rather than the app because, with my poor, old eyes, it is easier to navigate and enter data.
One thing to remember, dates should be entered day, month, year. With my husband's birthdate it is easy because the day is 31 and you get an error if you enter it incorrectly. My birth day is 4. I did mine first and submitted it. When I did his and saw the format, I immediately questioned how I entered mine. It was accepted so if there is a further issue I can show my card and id at the airport.