[MM3-users] Create a mailman-web admin user

I having a hard time understanding how to create an admin user for postorius (mailman-web).

The docs say at https://docs.mailman3.org/en/latest/config-web.html

Setting up Admin Account
<https://docs.mailman3.org/en/latest/config-web.html#setting-up-admin-account>

To create a superuser account in Django, run the following interactive command as|mailman|user:

(venv)$ mailman-web createsuperuser

However, which user in the mailman user mentioned?

I tried to do this as root, but login in as an admin doesn't give me any option to create new lists in postorius.  What am I missing / doing wrong?

regards

Roland