Default Redirect Page on apache

Hi, I have installed pi-hole with the Admin LTE interface with apache on my RPI and it works perfeclty for blocking website.
Problem is that I don't see the default pi-hole website blocked page, but the browser error page.

How can I configure it for apache (I don't want to use lighthttp since I have other web tool on my RPI)?

Here is an extract of my apache configuration file for the virtual folder which contains the pi-hole admin interface. Do I need to create another virtual folder?
What should I add in the apache configuration to make it work?

NameVirtualHost *:7070

<VirtualHost *:7070>
        #ServerName www.example.com

        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/pihole

        #LogLevel info ssl:warn

        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined

        #Include conf-available/serve-cgi-bin.conf

        <Directory "/var/www/pihole">
                AllowOverride All
        </Directory>
</VirtualHost>

Thank you for your answer

You should redirect the 404 handler on whatever handles the redirection at the root to the block page, which is installed by default to /pihole/index.php However, it looks like you have changed the default paths and so I don't know where it might be on your system.

/var/www/pihole/index.php is the admin page used by the Admin web interface in my case.
So this php admin page is also used to return the blocked domain?

Yes Pi-Hole will default display a (semi)blank page on port 80 instead of the ad.
So for this to work, these two lines would need changing:

NameVirtualHost *:80

&

<VirtualHost *:80>

And if you move back the files to where they belong "/var/www/html", you can point the DocumentRoot to them eg:

DocumentRoot /var/www/html

And redirect 404 errors in the VirtualHost section eg:

ErrorDocument 404 /pihole/index.php

There is normally this page at /pihole/index.php. Since you've changed the /admin folder to /pihole, you may have overridden it. So no, we don't use the admin page as a block page. We have a special page for that.