I bought this pack a while ago and when I tried to use it, I was quite confused by some tilesets. For the objects and character sprites, it's fine.
For the floors, it's more complicated. At first I thought they were autotiles (with the edges on the sides and one or more tiles in the middle for filling), but no. In fact they are 192x192 tiles for the filling with a last 192x48 tile for the bottom part. This is the only way to have tiles that match well.
And finally, for the walls, it's a mess. It's quite difficult to see how to arrange the tiles so as to obtain clean walls. It looks like 48x48 tiles but I end up with artifacts of other tiles or missing bits. So either it's badly done or I really don't understand how to use these tiles. And I'm leaning towards the first hypothesis, judging by the pre-built room number 12, where you can see visible cuts in the walls. It's really ugly!
Otherwise, the pack is relatively complete and offers a lot of perspectives to create a nice Lovecraftian RPG with a graphic style between Diablo and Fallout.