The policy engine is a single VM setup for the single or scale-out Prism Central. When you enable the policy engine for your Calm instance, a new VM is created and deployed for the policy engine. All you need is an available IP address that belongs to the same network as that of your Prism Central VM for the policy engine VM. You do not need to provide any public or private keys, or any Prism Central virtual IP addresses for this task. References: Nutanix Support & Insights, Calm on ESXi Deployment | Nutanix Community