How should I be using Users and Access Roles in MongoDB? The documents are confusing me a little bit and I'm not finding any answers on here or google. I'm using my own auth via passport-local-mongoose, so I don't need to use mongo's auth at all.

The docs say that I should create a new user for each user/application. Does this mean I create a user for each entry point, ie: one for mobile app, one for web service api, and then an admin for management? 

Or does this mean I need to make a new user for every single person who signs up on my site/app?

Every interaction with entry points (other than user registration) requires auth already, so creating a separate mongo user for every registered user seems redundant, however this is my first database so I'm not sure how things work as far as logging or security best practices. 

It is worth noting that I am currently storing users as collections with embedded documents for their data for easy lookup per user.
Because user security is handled with your application and it's application what contacts the database (not user), you don't need to create every user to the database as a database user.

However, it is still good practice to create a user for every application that uses the database system, so that application can only use those databases what that application needs to access and do only those operations (insert, delete, update,...) what that application needs to do. Nothing else.