my guess is they're premade loopz
The snare/toms tremolos and transitions between sound really good which is where most sampled kits fail. I wish they posted high quality samples I can hear that awful SoundCloud swoosh compression on the cymbals.
For a site that's almost exclusively used to stream music, it is hilarious and terrible that it consistently does that weird swoosh thing to cymbals haha.
I'm kind of stupid and thought the producer Zeus was somehow affiliated with this, and was confused because I thought it would sound like The Acacia Strain.