Did you set the vnc password for the user?

https://tigervnc.org/doc/vncpasswd.html

The apache2 setting you're looking for is DocumentRoot together with Directory. And maybe VirtualHost or Named Host or ServerAlias.

Depending how your webserver is configured now (using the default apache2 host?), you might want to add either a NamedHost or a VirtualHost with the new DocumentRoot.

Can't tell you how to do it via cPanel, but those settings are available in /etc/apache2/conf/apache2.conf or the like

It's common to have separate folders for different webservices like /var/www/html/yourwebservice.

Having Nextcloud, PiHole and LibreELEC/Kodi is something I wouldn't want to miss