The only XEN I know of is the Open Source XenServer Project (see: xenserver.org). The downloads on that site point you to Citrix XenServer pages. XenServer IS Citrix XenServer.
The Xen version of the VLM is incompatible with the current version of XenServer 7.2 because it is not packaged correctly for installation on XenServer. Also, the installation instructions are not designed for XenServer and don't even work when the support components for virt-manager are installed. It just fails miserably.
So what/how do you expect us to trial or install the "Xen/KVM" version of VLM when it is not properly packaged to run under XenServer.
If it is really a KVM only product, then it would be good to state that and just remove XEN from the marketing. If it does support XEN, then perhaps some better documentation could be put out there for installation.
I just want to run a trial of this product so I can decide if we want to go this route. It should be this difficult to do a trial.