Hey Varepo,
It's an 8x8 grid you have to use. You can have a look in tiled and open the "s4m_ur4i_dark_metroidvania_example_tilemap.tmx" it's an example to show you the exact setup. 8x8 is the base tile size while there are 16x16 tiles (4 times 8x8) tiles in all the sets to visually have smaller and bigger corresponding blocks.
Hope that helps
- Sam