Most of the stems of a RealDrum are mono but the overheads and room are stereo but Biab loads them as mono tracks.
If you are using wav files you can drag the source into the DAW but most DAW's won't take wma.

If you use Reaper you can generate up the Stereo or Stem wav/wma/aiff/m4a RealDrums with mono and stereo track directly in Reaper.
https://forum.cockos.com/showthread.php?t=260677

ReaTrak-biab-drums-gui-audio-demos.zip

https://www.dropbox.com/s/4mu71bmk1d2a8hf/Reaper-Biab-Drums-GUI.mp4?dl=0