The error message says- "...the destination folder....is not writable."
Usually caused by Mac Permissions.
See the answer about Security & Privacy from @Bob Somrak
Oh, and v10.4 is NOT the 'latest' . It is currently Lr-Classic v11.4 (and Camera Raw v14.2)
Regards. My System: Lr-Classic 12.3 Photoshop 24.5, ACR 15.3.1, Lightroom 6.3.1, Lr-iOS 8.0.8, Bridge 13.0.3, Windows-11.