a) mariadb/mysql
$ mysql -u adminusername -p
mysql> CREATE DATABASE _matomo_db_name_here_;
mysql> CREATE USER 'matomo'@'localhost' IDENTIFIED BY '_password_';
mysql> GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES ON _matomo_db_name_here_.* TO 'matomo'@'localhost';

Replace _matomo_db_name_here_ with the name of your MySQL database (if possible, this database should only have the Matomo tables installed).
Replace _password_ with your password.

b) apache
In /etc/apache2/conf.d/matomo.conf you must insert your domain.

  Apache22: Allow from .mydomain.de
  Apache24: Require host mydomain.de

And then restart or reload apache
  
  systemctl restart apache2

c) installer
Go to http://www.mydomain.de/matomo/

At mysql-setup use mysqli not pod.


d) Attention:
You must disable caching for matomo.

Example for APC
   you can insert php_flag apc.cache_by_default Off in /etc/apache2/conf.d/matomo.conf like:

	<Directory "/srv/www/matomo">
    	AllowOverride All
    	Options FollowSymLinks
    
    	php_flag apc.cache_by_default Off
    
    	<IfModule mod_authz_core.c>
        ...

e) php
To prevent some critical issue, you must set the following in your php.ini file: 
  always_populate_raw_post_data=-1
After making this change, restart your web server