I think that plugin and the project is no longer supported by Epic and Leap Motion. It’s for an older version of the Engine and if you read the first line it says “Due to an issue with Actor transforms in Unreal 4.9, we currently recommend that everyone build with getnamo’s community plugin”. Here’s the link to getnamo plugin which is the one that comes with the Engine. The GitHub has a tutorial as well which can help you get started with it.