You must first clone this repo and follow the instructions there, getting the Client ID and Secret from Spotify.
Once you have input the credentials (following the instructions on that repo) you can start that server which will run on port 8888.
In this directory you can now run
npm install
which will install all the dependencies for this project.
npm start
will start the app in development mode and you can open
http://localhost:3000 to view it in the browser.