CentOS 7 - Kolab install fails with brocken packages

[Dr. Hirn]

Hi,

trying to install Kolab 3.4 on a CentOS7 system. Like I did a few times 
before.
I'm following this guide here: 
https://docs.kolab.org/installation-guide/centos-community.html

When I'm running

yum install kolab

I get a lot of errors looking like

Error: Package: cyrus-imapd-2.5-108.1.el6.kolab_3.4.x86_64 (Kolab_3.4)
            Requires: libnetsnmp.so.20()(64bit)
Error: Package: libkolabxml-1.1.git.1422810799-29.1.el6.kolab_3.4.x86_64 
(Kolab_3.4)
            Requires: libboost_system-mt.so.5()(64bit)
Error: Package: python-kolab-0.6.0-3.el6.kolab_3.4.x86_64 
(Kolab_3.4_Updates)
            Requires: libboost_system-mt.so.5()(64bit)

Can anyone tell me what's wrong here?

Thank you very much!
Stefan