I would recommend doing what I do... search Google for something like, "npm passport express tutorial" or "express mongo user authentication tutorial". That will always result in some awesomesauce tutorial (most often, accompanied by a git repo.)
I'm not sure, but PassportJS doesn't seem necessary for this.
Maybe just use plain user authentication, starting the app off by checking for a user via Mongoose/Express, and if there is none, just having the initial user create an account with an email and password.