You must have an NSX manager paired with a vCenter before you can add a vCenter to the vCD.
But that doesn't mean you have to use any of the NSX functionality. In fact, you don't have to set up any of the NSX components or even license it (outside of the default NSX Endpoint license that gets generated automatically by default) other than deploying a manager appliance. You can still add external network(s) (backed by regular vSphere portgroup, standard or distributed), and then add a direct access org network to one or more external network for each organization VDC. Of course, the external network has to be managed manually at your network stack for separation between orgs and/or VDCs. Also, if you want each org to manage their own network/routing/firewall, you'll have to provide that means outside of vCD.
Bear in mind, if you're part of the vCAN program, NSX is usually included with vCD unless you choose to go standalone, and has varying license levels.
Thanks for that! Will see what vCloud sku they got.
If I deploy an NSX manager paired with a vCenter and I add external network(s) backed by regular vSphere portgroup, is it possible to have some routed org/vapp networks withou deployng any NSX controller ?
Routing must be done by an external router. As you are not using NSX, there is no router avaiable