Title.

.song_archive is apparently only written if --skip-previously-downloaded is set, but that doesn't make much sense to set on your first download. If you then later set that flag it looks for the archive, which isn't there, and wants to re-download everything.

.song_ids are also a source of downloaded info, so Zotify should use that as well.

I personally just populated the .song_archive file per below, but IMO this shouldn't be necessary

for f in **/.song_ids; do cat "$f" >> ~/Library/Application\ Support/Zotify/.song_archive; done