If this still didn't solve your issue you may have to reset your Office Keychain, in Keychain Access. Wait for it to open in your desktop application. If you are unsure how, refer to the following guide: How do I run updates on my Mac at Scotch?
To do so, follow this guide: What should I do if my Microsoft Applications are playing up?
To fix this you will have to close OneNote and exit the web interface (on your internet browser). OneNote may be experiencing difficulties if your Notebooks are not syncing.
