I actually solved it today, but thanks anyway. I will also post my solution for anyone looking for it.
So this applies if you want to create maps for worldadventu.re
In order to create walls or other things you don’t want your character to move over, you don’t need the collision editor at all. Just edit the tileset, click on the tile you want collision for and then create a new bool property “collides” and check it. That’s it.