This needs a level editor. I even commented on the video, the most recent one. btw, the editor should be called "Playtime creator"
If your on Pc, then you can just download the Unity Project. https://github.com/TheDevvDude/GrabPack-Unity-Project-1.1
If your on Pc, then you can just download the Unity Project. https://github.com/TheDevvDude/GrabPack-Unity-Project-1.1