Jupyterhub with multiple users

In my lab, I have 10-15 users who all use Python and some Julia. Mostly Python. I setup Jupyterhub 2.1.1 and I am able to launch my own notebook. I would like to colloborate with other members of the team.

So, I run
jupyterhub -f ./jupyterhub_config.py

When another user tries to login she gets “…/jupyterhub-singleuser. Does have access to this file?”