You have two options to get the Printer Installer password:
Reset the MySQL root password
Find out what the password is from the Printer Installer settings
There are lots of articles on the net about how to reset the MySQL root password, but it’s fairly easy to find the database password for Printer Installer. You can find it on the Printer Installer website server in the following file:
The database settings are listed at the start of the file, including the root the password.