Pimcore behind apache reverse Proxy

Hello Community,

Today I installed pimcore on a debian 10 , apache2 , php 7.3 webserver
It’s behind a apache reverse prox where we have other sites on.

I can access the site with my-site/pimcore
My problem is, not everything works yet. Css and pictures don’t show
In the documentation there was not a lot of information about reverse proxy setup, so I wanted to ask here

my apache conf on the host
DocumentRoot /var/www/pimcore/web

SetEnvIfNoCase Request_URI "\.(php)$" no-gzip dont-vary

AddHandler php7.3 .php
Action php7.3 /php7.3
Alias /php7.3 /usr/lib/cgi-bin/php7.3


<Directory /usr/lib/cgi-bin>
    Options ExecCGI FollowSymLinks
    SetHandler fastcgi-script
    Require all granted
</Directory>
<Location /var/www/pimcore/web/>
Options FollowSymLinks
Require all granted
AllowOverride all
</Location>

This is the apche conf on the proxy

Define VPATH /pimcore
Define DS_ADDRESS IP adress

Alias heicumedia ${VPATH}
ProxyPass ${VPATH} “http:// ${DS_ADDRESS}”
ProxyPassReverse ${VPATH} “http:/ /${DS_ADDRESS}”

<Location ${VPATH}>
ProxyPreserveHost On
Require all granted
SetEnvIf Host "^(.)$" THE_HOST=$1
RequestHeader setifempty X-Forwarded-Proto https
RequestHeader setifempty X-Forwarded-Host %{THE_HOST}e
#caused header error after login on e.g. Chrome, mobile Browsers, etc.
#RequestHeader edit X-Forwarded-Host (.
) $1${VPATH}
ProxyAddHeaders ON

How do I set it up behind a reverse proxy ? Is ther something I have to change in the .htacces file
Could you help me please.