after installing the vSphere Web Client, you will have to Register it with the vCenter
1. From the vSphere Client, start > All Programs > VMware > Vmware vSphere Web Client > vSphere Administration Application, accept the browser security issue (if appears)
2. Click Register vCenter server
3. In the vCenter Server URL field, enter the vCenter server Registration URL.
4. In the address field, enter the vSphere Web Client URL
4. “Install the certificate and do not display..”