thanks for your answer. Unfortunately I was not successful to follow your hint.
Exporting a scan at Microsoft Lens it offers me below options:
Tapping "Weitere Apps" there then appears an item "In Dateien sichern", where this folder is shown
Auf meinen iPhone
However, below Boxcrypter there are no subitems, so no folder can be selected.
Can you please give me more details on how to get a scan exported to a Boxcryptor folder?