You can import the scores in MuseScore app from your mobile device. Simply tap the '+' symbol on the top of the SongBook section and select a score to upload.
To find 'SongBook' section tap 'My Library' tab --> scroll down to the 'Available Offline' section --> SongBook (Locally saved score).
SongBook feature is available for PRO/PRO+ users.
Keywords: import, mscz, SongBook.