The demo is now in a secondary download grid_building_inventory-3.1.0.zip. I didn't have the latest demo up there when you posted the question sorry about that! The demos are separate from the main package to reduce clutter from the plugin (and those people's main game projects). Just posted the update to the plugin so I recommend updating while you're at it. I'll have a new tutorial out soon. Let me know if you have any further questions. Thanks!