Please Read : Unity.EyapLibrary.SceneManagement/Packages/eyaplibrary.scenemanagement/README.md
This scene management is in a separated package cause I still have mixed feelings about it. I found it usefull for single-players, but still think it may be improved.
Overall, I don't really like the scene management of Unity (with the .asset file), and think it could be improved - It feels to me that every approach has its drawnacks...