OK, it looks like ZM forces HTTPS after the initial connection, so you'll have to change the Listen port in /etc/httpd/conf.d/ssl.conf. Use a different port to the one in httpd.conf.
You'll also have to edit the <VirtualHost> line in ssl.conf and change the port number there as well.
Change myPort to whatever port number you used in the Listen line in the same file.
Then, when you load ZM in your browser, use http
s://ip.add.re.ss
:port/ or the browser will likely try the default SSL port (443) and not be able to connect.