You only need to put it inside your Ren'Py project folder. Then, when you create a new project, the launcher will ask if you want to use a template or not. https://www.renpy.org/doc/html/template_projects.html
All the functionality is already included so it works as a template; all you have to do is unzip it in your projects folder such that it looks like any other project.
This template is not a tutorial - it's for people who want to try their hand at customizing their projects beyond the reskinning the default project offers. I do have a website for tutorials if that's what you're looking for: https://feniksdev.com/navigation/