192.168.0.1 with the IP of your server
recalbox/rom with yhe path on your server
the username and the password
I figured this out finally.
sharenetwork_smb1=ROMS <- This is the ROMS folder on the pi in the recalbox /share folder
@192.168.0.1:recalbox/roms <- This is the shared folder on your server.
But in order for this to work, you need to have the same folder structure as the /share folder on your pi.
So basically create a share folder called roms. Then inside that folder use the same folder names for each system on the pi and place the roms in there, then it will work.