Hi, your need import the Root CA of the vcenter server to the Citrix Server.
Connect of the citrix desktop, open the internet explorer and step and step:
How To Install the Root Self-Signed Certificate from vCenter 6.0 -- Virtualization Review
Other links:
Using the default VMware vCenter server certificate in XenDesktop POCs | Citrix Blogs
Setup the default VMware vCenter server certificate in XenApp | Ervik.as - EUC, HCI, Cloud and Virtu...
