As I continued to try to track down the problem, I found the tutorial titled Protect phpMyAdmin On An ISPConfig 3 Server (Debian)
and after looking through it, I decided to try it out. While going through the steps, I found that the /etc/apache2/conf.d/phpmyadmin.conf
file did not exist. After creating it and following the rest of that tutorial, I am now able to access my PhpMyAdmin databases, but in the ISPConfig3 Monitor tab, it still shows an error with the MySQL-Server. Any direction on how to fix this would still be appreciated.