Thanks for writing in, and welcome to the community! Both @Wade_Oram and @Geoff_Coupe are correct in their replies above.
Before adding anything on the Nucleus side - I’d run through the help article above and make sure you have all the proper share settings to your local music folder on the mac side.
Certainly let me know if you run into any additional questions along the way as well!
Thanks everyone for trying to help. Let me start by saying I’m computer illiterate. I somehow got some tracks moved over by dragging them over from Music to Roon. I tried the above instructions but am getting an error.
You entered the path to a folder on the Mac, but you should have entered just the IP address of the Mac followed by the name of the share. A share is essentially a name under which the Mac advertises the folder (and its path) on the network. A shortcut to the folder, if you will.
You must first set up your Music folder on the Mac to be shared on the network. This will assign a share name to the folder, which you then use in Roon: smb://192.168.1.39/your_share_name
The details of how to do this are explained here, on the page linked previously by @Geoff_Coupe: