I have searched for the specific error the installation wizard is throwing (Connection Error: Permission Denied(13) here and come up dry.
So, in troubleshooting so far I have:
Reset the root password (and cleaned out other root accounts so that only localhost and 127.0.0.1 remain.
Enabled remote login for MySQL and logged in successfully with the root MySQL account
Connected to the local client from the command line using the -h switch to connect to 127.0.0.1
Everything is set up according to the instructions on the ProcessMaker site. (even found a few typos in that process LOL)
I am stumped. MySQL is accepting connections to local users but the install wizard won't connect.