Howdy @WardK , welcome to PhotoStructure!
PhotoStructure uses SQLite for your library database. SQLite requires a local disk.
PhotoStructure does detect if your library is on a remote filesystem, and automatically applies a workaround, but, unfortunately, OneDrive and DropBox folders look like they’re on local disks, but are incompatible with SQLite. More details are here.
If you pick a different directory for your library, say C:\Users\WardF\Pictures, or C:\Users\WardF\PhotoStructure, everything should work fine.
If you want PhotoStructure to automatically organize into a different directory, know that you can change your PS_ORIGINALS_DIR to be a directory in OneDrive, and that should work smoothly. Details on how to change these “advanced” settings are here:
Cheers,
Matthew