Hi Bill,
Generally, routers mount USB drives by their disk label, share the drive using Samba (SMB/CIFS) and they usually have an option of whether to require a userid/password for access.
Using your info the connection path would look something like below:
PC: z: --> \\BTHUB4\usb1\Music
Mac: cifs://BTHUB4/usb1/Music
In Moode NAS config
Source name: <a friendly name like Music or MyMusic>
Fileshare protocol: SMB/CIFS
IP address: <the ip address of BTHUB4 router>
Remote directory: usb1/Music
Userid: <either the admin id of the router or a dummy id like aaa>
Password: <either the admin password of the router or a dummy password like bbb>
-Tim