Sync Mac & Windows user profiles to OneDrive
OneDrive allows you to sync to whatever folder you desire. In your case, point it to a OneDrive folder in the shared Windows document folder. The Mac will simply have this folder in its Document folder as well. Whenever Windows is running, it will sync with Onedrive and populate the shared folder. Of course, since you don't have OneDrive on the Mac, it won't sync. You could always put OneDrive on the Mac, and point it to the same folder...