Installation:

Install a "LAMP" server via your distribution:
* web server 
  + with php capabilities
* sql database (mariadb)
* email server/ability to send emails (optional)

You also need: 
 * jquery
 * dhtmlxscheduler

cd html/js
wget https://code.jquery.com/jquery-3.7.1.min.js
cd ..
wget https://github.com/DHTMLX/scheduler/archive/refs/tags/v6.0.5.tar.gz
tar -xvf v6.0.5.tar.gz
ln -s  scheduler-6.0.5 scheduler
rm v6.0.5.tar.gz

Example for debian: 
webserver:
 apt-get install apache2 openssl python3-certbot-apache php-mysql php-json
sql database:
 apt-get install mariadb-server mariadb-client

Copy the contents of the html directory into your webserver tree

create database and database user

restore database from backup:
TODO

edit konfiguration.php and adapt to your installation

login with admin user: admin@admin.de pw: 4024ae463a4ef9ff455705afe54f83c3