Before Roon will be able to access your music library that's stored on your Mac OS device, you'll need to first ensure that the folder is properly shared. Once the folder has the proper share settings applied, it can be added as a watched folder in Roon. Follow the instructions below to properly share your folder:
Accessing Share Settings on the Mac
On the Mac, go into System Settings>General and Select Sharing. From there, enable File Sharing and click the āiā icon beside the switch:
Scroll down and click the '+' button to add your folder:
Select your folder and click Open. Ensure Permission is set to "Read & Write." Then click Options and confirm SMB File Sharing is enabled for your folder:
Sometimes it is helpful to re-enable Account specific Windows file sharing by clicking the checkboxes (see above) off and on again.
From there, head into Roon Settings>Storage>+ Add Folder > + Add Network Share:
Under Network Share Location add "smb://" followed by your Mac's IP address (System Settings>Wifi or Ethernet>Details) followed by the folder name. The complete string should look like:
smb://IP_address/folder_name
Then, add the username and password you use to log into the computer. Lastly, select "Add network share" and Roon will add your newly shared folder.
Please Note:
On early releases of macOS Catalina, you may receive an error when adding the Network Share. One thing to try is to click the File Sharing checkmark Off, then On again in System Preferences > Sharing.
Note: If you are unable to share the account properly and the username is grayed out, this might be because you don't have a local account on your Mac. You may need to create a new local user account and try sharing via that instead.