Indeed, port is 443 (you connect to the SDK, not the web client).
Then, I would not use the SSO administrator for this use, it is the last thing to do. Create a vCenter local account (VCSA or Windows one) and grant it the rights to administrate the vCenter, this will have a side effect : you will know that it is View solution that is doing tasks you'll see in the vCenter events. It is imho a best practice to create dedicated accounts for such services (vCloud Director, SRM, View, etc.).
