Thank you for the replies and help. stevesh, that is a great idea about the 'custom' folder tree, that will be so helpful. RodG, I've re-checked permissions on cache and other folders, and they seem to match what the installation instructions call for.

Am getting this message: 'You don't have permission to access //www.mydomain.com/catalog/zc_install/index.php on this server.'. I could be wrong about the host/server side, for sure. Even though there is already a cart working there, could that permission from them be at a folder level where I need to get my new demo folder modified by them on the server? It has been a very long time since I first worked with the installation of Zen Cart and am re-learning. Appreciate the help.