Hey thanks for the reply! I'm biased since I'm developing in Godot but here's a link to the 2x2 mask and 3x3 minimal mask. Personally I like using 3x3 minimal but if your target is rpg maker I'm not sure what they use
https://github.com/godotengine/godot-docs/issues/3316#issuecomment-614923124
hmm, my download had a godot folder with an autotile.png but no project file (project.godot) or .tres file (which I think can hold bitmask definitions).
As far as I know, with at png I need to use the Godot tilemap tools to manually draw the bitmasks. Again, I'm new to all this so I could easily be missing something obvious. Apologies if that is so. If you get a chance to take a look it would be greatly appreciated. These tilesets are amazing, looking forward to building out a game with them.
cheers