NAS service on your network

[the_bertrum]

I would like to use two raspberries, one to use as a server and the other just as a player. However, I'm not sure which settings to use.
For the player I think you have to go to renderer and activate UPNP and for the server in file sharing settings activate SMB or NFS or DLNA.
besides I don't know which one to choose, I specify that for the server the music will be stored on a USB hard drive.
and that's pretty much what I think I should do but please let me know if I'm missing something

Assuming you mean both "server" and "player" will be moOde devices, then plug the USB into the "server" and allow the MPD database to build (update library), then enable SMB in the system settings.  Now over on the "player" configure a "remote NAS source" in the library settings, scan for SMB shares then select the one corresponding to "SERVER/USB" (not sure what exactly it would be called), mount it then update the library.