Additional team and channel-related features and issues within Microsoft Teams for Education
Hi MattM25,
I'm Nik, an independent advisor here to assist you with this.
Your team notebook is located in the SharePoint team site's document library. To go there, you can first navigate to your OneNote file in teams app > select "Open in browser" drop-down and select "Open in app" option. It will open your file on your desktop app and sync.
Please ensure that you have signed in on you OneNote Desktop app with your School account.
Also, that your OneNote desktop app notebook pointing to your school class(Team) location.
Please refer attached screenshots to confirm that the OneNote file that you opened from Desktop app pointing to right file location in MS Teams to sync properly.
Regards
Nik