The easies way to get the code up'n running is to install a new Alloy MVC site using the Visusal Studio integration, and then you can do a git clone of this repository inside the solution folder.
When that is done you need to add the VersionsComponent.cs to the .csproj and build. To transpile the React components you first need to run npm install and then gulp react.
To read more about the sample please head over to the blog post: http://world.episerver.com/blogs/magnus-stalberg/Dates/2017/1/creating-a-react-widget-for-episerver-cms/