When scanning to your OneDrive for the first time, you need to authorize the access.
You will get this notice after the initial scan:

If you do not authorize the initial scan you will get a follow-up email:
If this happens repeat the scan of a document and authorize the access.
A successful authentication email will look like this:

Your successful scanned items will appear in your OneDrive, Apps, Scans for PaperCut MF folder
