Cannot log in site despite having credentials from settings.php Ubuntu 16.04, Drupal 8 managed through ISPConfig 3.1

I'm trying to log in at mysite.com/index.php/user/login and I get bad username or password. I have copied and pasted from the settings.php file and everything.

This is a box that was setup for me by someone else who, when asked for the credentials, directed me to just get them from settings.php.

The only thing I can think of is that I'm somehow getting a site-login instead? But it's a fresh Drupal 8 install with no config. 
Is there any other source for the password or alternate password for it?

I've tried going through ISPConfig and changing the database password there but it just breaks the whole site:


  “The website encountered an unexpected error. Please try again later.”


So I just revert to the snapshot.
Okay I see what happened now. 

I was trying to login to Drupal and not to the database, but I was getting the DB password from settings.php.

On the Drupal sites I setup in the past I used the database user and password as the Site Maintenance Account’s credentials, so I’m used to them always correlating. Since someone else set this one up they put the user and pw to something different. It's probably a security hole to do it the way I was doing it so I guess I need to fix that.