Once the NSX Manager OVA is deployed you can login to the NSX Manager using the credential you specified (admin) to then register your vCenter Server and Lookup Service it’s also worth a review of the settings specified during installation (specifically the network settings).
1 – Log in to the NSX Manager virtual appliance.
2 – Under Appliance Management, click Manage vCenter Registration, click Edit next to the lookup service URL and the vCenter Server and type these in. It’s worth noting here that I have a load balancer in front of my PSCs (SSO Servers) so I have specified the VIP URL. Also in vSphere 6.0 and above the port used for this lookup changed from 7443 to just 443. Click OK and then give it a few seconds to confirm the Lookup and vCenters both show as green and connected.