I am using the identity appliance 220.127.116.11 Build 2496259 and the VMware client integration plugin works with vRA 6.2.1. When I first installed the plugin, there was a pop up that asked me to allow the plugin to run and I had to select 'allow',. I am wondering the plugin is being blocked somehow in the web browser, or there are some security settings in the browser that stopped the popup asking you to allow it to talk back to the identity appliance.
You could try to uninstall the VMware client integration plugin from add remove programs, remove any VMware plugins used in the browser and check that there is nothing blocking popups in the browser. Then, re-install the VMware client integration plugin and see if this helps.
Or you could try another browser - I am using Firefox. I've never had to configure any SPN's for the identity appliance.
The pop-up did show up and is allowed. I tried multiple browsers (IE, Chrome, FF) to no avail.
So the tick-box works for you then ?
Which version of the client integration plugin do you have installed? I ran into the same issue. I had the 5.5 version installed. I installed the 6.0 version and everything worked good in IE & Firefox. In chrome you have to enable NPAPI Chrome 42 breaks the vSphere Web Client Integration Plugin