Right-click the Instrument track and choose 'Split Instrument Track' to get separate MIDI and synth audio tracks. Then assign the drum map to the output of the separate MIDI track. Depending on what other MIDI output ports (both physical and virtual) are available in the project you may need to change the default output port assignment of all notes in the drum map to the Session Drummer port (hold Ctrl+Shift while changing the output asignment of the last note after changing the first).
Session Drummer will automatically show kit piece names in the Drum Pane of the PRV without a map applied, but looking at the Drum Map will let you see exactly how note numbers/pitches are mapped to the different kit pieces/articulations.