After having installed the vCAC Design Center, every attempt to run it failed. The GUI would not load. In my case, the Windows Application log recorded the error:
.NET Runtime Event ID 1026 in Application CloudUtil.
Framework Version v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Reflection.TargetInvocationException.
Only when I tried calling CloudUtil.exe from the command line did I get an error message indicating that the application could not establish a trust relationship with the vCAC MOdel Manager. This meant that the self-signed SSL cert was not trusted.
Fix:
Logon to vCAC administration portal and import the SSL certificate into the “Trusted Root Certification Authorities\Local Computer” physical Certificate Store.
After this, I was able to successfully launch the vCAC Design Center.
Brian Ragazzi 
Thanks for this info. I was having the same issue and couldn’t figure out the cause.