Now, Sharepoint and OneNote both block any attempts at working with local files and there seems to be no mechanism for downloading the actual OneNote files to store them somewhere else. When we first started using OneNote, the files were stored as normal files and we could upload them, download them, etc. We have a large number of legacy OneNote files storage in Sharepoint via Office 365. To learn how to import notes or notebooks that you've exported, see Import notes and notebooks.Said in Download OneNote Files from said in Download OneNote Files from Sharepoint:

Attributes will be stored as metadata in the HTML or ENEX file.If exporting as a multi-page HTML file, you will receive an HTML file for each note, a single folder that contains all note resources (e.g., attachments, files), and an index that links all of the HTML files.If exporting as a single-page HTML file, you will receive a single HTML file with all notes and a single folder that contains all note resources (e.g., attachments, files).If exporting as an ENEX file, you can select the maximum file size of each ENEX file between 300 MB to 2 GB.Evernote currently supports exporting up to 100 notes at a time or entire notebooks.Choose the file name and location, then click Save.Select Export as file in ENEX format (.enex) from the menu and click Export.Right-click on selected note(s) and select Export Note(s).Click on a note or hold down the Ctrl key and click to select multiple notes.The file will be saved to your computer's desktop. Check or uncheck the attributes you'd like to export with your notes (e.g., tags, created date, author).

Select a file format (ENEX, single-page HTML, or multi-page HTML).

Right-click on selected note(s) and select Export.Select a notebook or the specific notes that you want to export.

Onenote export notebook