The DrumSep model divides the drums stem into 4 types: 'kick', 'snare', 'cymbals', 'toms'. The model from this github repository is used. The model has two operating modes. The first (default) first applies the Demucs4 HT model to the track, which extracts only the drums part from the track. Next, the DrumSep model is applied. If your track consists only of drums, then it makes sense to use the second mode, where the DrumSep model is applied directly to the uploaded audio.