In the unlikely event that you have problems reading the MRZ:
Check that the MRZ is "clean"
When scanning, minimize light influences and reflections from the outside
Scan preferably without using your phone's flash
Keep the MRZ as large as possible in the active part of the scan template
When necessary and depending on the phone's camera, landscape scanning can be an option
Turn on the "overlay" in settings / notifications as an extra visual aid