Thanks for writing in, and welcome to the community!
Since you’re getting the ‘Unauthorized’ error specifically, we’ll likely need to double-check your folder/file share permissions on the Mac side of things. Think of setting up a storage folder in Roon as a handshake - one hand is getting the location set up and activated within Roon, and the other hand is ensuring Roon has proper permission to access the files within the drive/folder/location you’ve selected within your storage settings.
Here’s a KB article that breaks down the necessary steps within your Mac settings to ensure Roon has proper permission:
Let me know how things go after going through the above steps!