It rather follows the concept of "libraries", but by default the Windows 10 "music library" only consists of the user's music folder.

You can add more folders through Windows Media Player.
Obviously, media streaming must be manually enabled. I probably forgot when and why I did it. If the music files are not in the music folder (for which I see no reason) then that other folder would have to be added to the music library, first. Enabling media streaming is pretty much a one-click-action. It's well described e.g. here:
They also list more capable alternatives, if you need more flexibility. I don't actively use that stuff. It just happens to be around, so I thought I'd answer the question if the Ultra can deal with it. It can, if media streaming is enabled.