i was able to install the missing modules.
Could it be that the nginx configuration is outdated or not working with nginx php-fpm in front of apache?
I am trying to get it running but without luck so far.
The login to kolab-webadmin causes the following error
PHP Fatal error: PHP Error: Login failed. Unable to decode response (POST)
I think this is not working because of not working rewrite rules or of not working fastcgi_pass_header X-Session-Token