Hi! Thank you for your kind words about our asset pack :)
Let's try to help you out :) As our Tilesets are prepared, you should be able to use them without any issue. Godot has tools for using Tilesets and creating Tilemaps: https://docs.godotengine.org/en/stable/tutorials/2d/using_tilesets.html#doc-usin...
Our Tilesets come in png format, adapted to a 16x16px grid. We're not sure what could be preventing you from implementing it, as it's really a standardized system. If you continue to have problems with implementation and believe it's due to our Tilesets, please don't hesitate to explain the issue in detail here or at our email: contact [at] muchopixels.com
Cheers!