OMSI Crossing Editor problems

I've been wanting to work with the Crossing editor for some time, however every time I try to open something with it I get an error "Datei nicht gefunden." Sadly I know little German but I can only assume I've likely did something wrong? Currently the Crossing editor is sitting in the main folder of OMSI, does this matter?

We will create a documentation for that in future, too.

You have to place the "SDK" directory into your "OMSI" directory! Then everything should work!