This thread is specifically made for experienced modders to fix this map file, it does not properly work. If you don't want to fix it, you can make your own map out of it as a template. You can also comment any troubles you're having on the map in this post. Lastly, the map files are inside the .zip file in the attachments section if you want to modify it.
I got bad news for you: the .mis file is empty that's why you can't load your map, you will have to recreate your map but you can still use the art folder and the .ter file by changing the terrain's path in the .mis file