However, after that was addressed, there was another other issue that was uncovered, issues that also related to the admin interface but don't seem to be immediately connected to the initially reported issue. Specifically:
While I can submit the login form, I don't seem to really seem to be able to log in. Every time I've entered my credentials I've been redirected to a Django admin login page, with the URL varying somewhat. I know it's treacherously easy to mistype a long password, but when I was getting login failures I used copy-and-paste to assign the same password as I was trying to log into again. So while mistyping a password is an easy trap to get stuck in, I adapted by trying an approach where the reassigned user password is the same pasted password as in trying to log in.
I tried manually entering the first and last character to eliminate the possibility of including unwanted whitespace, but it still doesn't work. Django has claimed incorrect login details for every administrative set of credentials I've offered. (I've also used python manage.py shell to confirm that the username for the superuser is what I thought it was: admin.
What if anything do I need to be able to log in to an administrative account, created by python manage.py createsuperuser?