As far as I know there is no Cisco ACI integration in vCD. Either you use NSX or you can only manually map vSphere port groups to tenants and provide an L3 gateway outside of vCD (but you can't manage that in vCD either).

Maybe you can build something with the vRealize Orchestrator workflows to allow at least a small amount of networking self-service. Starting with vCD 9.5, the workflows can be started in the vCD GUI by end users. For example, if a customer needs a new Org network, he can start a workflow and vRO configures ACI and maps the vSphere port group into vCD.