Yes! Just the .rmmzproject file. If there's any way I can prove it I'll try.
I did unclick the DLC on Steam, let it update (so the folder was gone from my files), then re-clicked it so that the folder was redownloaded, but there still wasn't any .rmmzproject there.
Here's a picture of the demo folder with the tileset, but also the demo folder without the .rmmzproject file :0
