Some files could not be migrated because you do not have access rights. Import the files you want to migrate from [Import PDF] in the [Preferences] screen.
For Android 11 or later, along with the security enhancements that are made for the operating system, it is possible that access rights to the files have been lost.
Import the files you want to migrate from the [Preferences] screen. For details, refer to Importing PDF Files (Android 11 or Later).
The files that were not migrated can be checked by tapping [Results of the file migration] in the message.
If some files were not migrated, the files can also be checked from [Results of the file migration] under [File Management] in the [Preferences] screen.