Hey restless, I’ve been using Godot 4, so I’m not sure if it works the same way in Godot 3.
I’m also not certain whether the tiles will work with autotile, as I was placing them tile by tile in Godot 4. I did manage to get autotile working in GameMaker, though. I believe they should work, but I can’t really guide you on how to implement it in Godot 3.