All I can do is tell you my set-up & that it works.
Directory structure is media/Music/artist/album/trackname
Windoze has the media share mapped as *V:*
iTunes has it’s library location set to *V:Music*
I manually copy the iTunes library file to *V:Music*
Firefly recognises the playlists and all songs appear to be there.
Please note the capital M. I initially had problems getting Firefly import the iTunes playlists because I told iTunes the path was music, instead of Music.