This is Kolab Winterfell on Fedora 26.
I get this error:
PHP Fatal error: Uncaught Error:  operator not supported for strings in /usr/share/kolab-webadmin/lib/kolab_client_output.php:159
The variable script is initialised as a string, but then used as an array.
It seems the version of PHP (7.1.8) in Fedora 26 does not like that.