Do not use the Django admin unless you really know what you're doing.
You should never need to access it unless you are familiar with Django or are instructed to do something here by one of the developers.
The Django admin is basically a web interface for the postgres database.
As of Tactical RMM v0.4.19, the Django admin is disabled by default.
To enable it, edit
/rmm/api/tacticalrmm/tacticalrmm/local_settings.py and change
sudo systemctl restart rmm.service.
Login to the Django admin using the same admin credential that was created during the
install.sh script (ie the web ui login).
If you did not save the Django admin url (which was printed out at the end of the install script), check the
local_settings.py file referenced above for the
ADMIN_URL variable. Then simply append the value of this variable to your api domain (
https://api.EXAMPLE.COM/) to get the full url.
Example of a full Django admin url: