Thank you! These tilesets are currently in an older format which requires you to parse the texture atlas metadata, as the spritesheets do not have aligned tiles. However, you can drag/drop the individual tile PNGs into Sprite Fusion and it will be able to import the pieces which are multiples of the tile size.
In the future, I'll update this asset pack to use my newer spritesheet format, which will make them much easier to use. I have more tilesets here which are newer!