To get the UnRaid file server synced with the Nas4Free ZFS file server, I will use rsync.

as reference, I played with these commands already to push data from the NAS4Free server to the UnRaid server.
Rsync  “Work” folder sync.
rsync -r -a -v -e ssh /mnt/Pool01/work  root@192.168.8.224:/mnt/user/work/

Rsync – “photo” folder sync.
rsync -r -a -v -e ssh /mnt/Pool01/media/photo/  root@192.168.8.224:/mnt/user/photo/

Rsync – “music-unsorted” folder sync.
rsync -r -a -v -e ssh /mnt/Pool01/media/music-unsorted/ root@192.168.8.224:/mnt/user/multimedia/music-unsorted/

Rsync – “music” folder sync.
rsync -r -a -v -e ssh  /mnt/Pool01/media/music/ root@192.168.8.224:/mnt/user/multimedia/music/