Well, I am using POWWEB with no issues! I kind of doubt that the tech on the POWWEB end really "did everything right"
So, go to your POWWEB Member Operations page. Then find the link for Manage MySQL under Scripting and Addons. Click on that link.
At that point you should see a list of databases. One of those (if there are more than one) is the one for Zenphoto and what you need to place in the database name field. If you click on that databas you will see a list of users on the right hand panel. One of those is the user ID that you need to supply to Zenphoto. It is the password for that user that you supply in the password field.
The last thing you need is the database server. It will take the form `<your powweb user id>`.powwebmysql.com. It goes in the database server field.
So, remove the zp-config.php file from your installation and re-run the setup.php program providing the above details.