FATAL ERROR: Can not init steam

[Mudbill]

Does the folder have the underscore in the name? It should be named exactly "custom_stories" to be detected. As long as a correctly configured CS is placed in that folder it should show up in the menu in-game.

PS: Just as a reminder that if the Steam copy updates in the future, it's possible that update will overwrite the retail version of the exe file you have, just in case something would seem to suddenly stop working.