I have recently reinstalled Zenphoto on my webpage as the previous old version just quit working all together, but instead of going through a third party installer, I downloaded it direct from Zenphoto. However I can't get it to work. If I go into the website/zenphoto is brings up the message: The site is undergoing an upgrade. Please return later.
If I go into the website/zenphoto/zp-core/setup.php it gives me the message - A configuration error occurred. Please return later.

I asked my hosting provider and they thought the database had been setup correctly, but couldn't work out why it wasn't propagating properly. Do you have any other suggestions of where I can look for possible glitches?

Have managed to get it all working again with some set up help from my provider.

What you encountered was the maintenance mode that is on by default after running setup. That is described here: https://www.zenphoto.org/news/installation-and-upgrading/ Since you should be loggedin with admin rights you should have seen a toolbar with a note to disable it. Otherwise it is possible via the config file via the site_upgrade_state parameter.