The following steps will help you import your notes from OneNote easily.
Go to Notesnook Importer and select OneNote
from list of apps.
Click on Start importing
Login to your account
Give permission to Notesnook Importer to access your notes
Wait while Notesnook importer imports your notes from OneNote account. Once importer completes processing, download the .zip file.
After you have downloaded the .zip
file, go to Notesnook app > Settings > Notesnook Importer and click on “Import from ZIP file” & select the .zip you downloaded earlier.
Once importing completes you should see all your notes in Notesnook. If you face any issues during importing, report it on github.