I mean you have to read the licence on every single picture, because it may not be the same as the licence on the last picture you downloaded from there. You can't assume the licence is the same across the platform in the same way you can on Pixabay or Unsplash, because each person sets their own rules. I don't know how many there are either. I just know you have to read the licence for every single picture. I've seen some photographers add their own criteria, so that would be an add-on to any standard licence.