YoYoYo Engine

[Etholux]

        I just downloaded GameMaker Studio 2 and The IWBTG Studio Engine YoYoYo Edition v1.51. I tried opening the GMX file that came with the engine with GameMaker, but it gave an error saying it was not a valid project. In Klazen's Fangame Development Tutorial (https://klazen.com/IWBTG/tutorial/dev_tutorial.html#Environment_Setup), it says to open a GMZ file that is in the extracted folder, but I am sort of lost at this step. Do I need to do something different because the tutorial is outdated? Do I need to do something that can't be done with the free version of GameMaker?

[Gravitoon]

You need the GMS2 engine:
https://iwannacommunity.com/forum/index.php?topic=2536.0