Data Persistence in 2D Game Kit

This question relates to the 2D Game Kit platformer toolkit released with Unity 2017.3

How do I activate data persistence in the game kit? In the sample game, Ellen's inventory is saved and persists between scene transitions, but when I make my own scenes this does not seem to occur. The documentation for data persistence is very unclear. It points to the PersistentDataManager class, but it doesn't describe how it is used. Do I need to create an instance of this class within my scene?