vCenter Server 8.0.x
VM Template (VMTX) synchronization requires trust between the Publisher and Subscriber vCenter Servers
To sync VM Templates to Subscribed Libraries, all vCenter Server(s) must participate in Enhanced Linked Mode (ELM).
Existing vCenter Servers can be linked by following the steps from the below link:
Repointing vCenter Server to another SSO Domain
Once the vCenter servers are in linked mode, follow the below steps to sync the VM Templates (VMTX).