From the online documentation, the Bridge II appears to turn your DAC into streamer (a UPnP renderer). That means it essentially performs the same function as the CXN. Cambridge Audio offers a nice diagram of a UPnP based system on this web page - What is UPnP?
Using the diagram as a reference, if you have music stored on a computer, you either need to share the folder it's stored in or install / enable UPnP / DLNA on that PC.
If you're using a streaming service such as Tidal or Qobuz, you'll need to find a UPnP app (or perhaps a plugin for the UPnP server software) that lets you access those streaming services and select the Bridge II as the renderer.