Can't access my already created tracks with the TM2 Makers

[Mixlas]

Hello, I hope this is the right place to ask about this.

I wanted to try out the TM2 Stadium Maker (Or any of the environments). This is the screen where you can put together your own campaign:



However, if I click on one of those empty spots to add one of my maps, it tells me that there are no files nor folders that are supported.



I'm able to create a track from within Stadium Maker and that loads perfectly fine. Weirdly enough, that track cannot be started using the regular Stadium game. There are probably two different file formats for maps, but I'd like to know how I can make my tracks be recognized by the Stadium Maker.

Thanks in advance!