To deploy a 2-node ONTAP Select cluster with synchronous mirroring and high availability, you need to take the following two steps:

Ensure that the ONTAP Select Deploy VM resides at a third location other than the two data centers. This is because the Deploy VM includes a mediator service that connects to each node in the active two-node clusters to monitor the HA pairs and assist in managing failures. The mediator service maintains the HA state information at a dedicated iSCSI target associated with each two-node cluster. If the Deploy VM is halted or fails, the mediator service is unavailable and HA capability is lost for the two-node clusters1.

Use ONTAP Mediator service to make sure that you have a quorum for the two nodes. When a cluster consists of two nodes, it is not possible to achieve the quorum required when a node fails or loses communication. To resolve these types of split-brain situations, the mediator service helps the surviving node to determine whether it should take over the partner node or halt itself1.

You do not need to install the SnapMirror Sync license on the cluster, as it is not required for synchronous mirroring. You can use the SnapMirror Synchronous (SM-S) feature, which is included in the ONTAP Select Premium license, to create a zero-recovery point objective (RPO) mirror relationship between two volumes on different clusters2.

You do not need to use ONTAP Select Deploy to install the nodes on the physical hardware, as ONTAP Select is a software-defined storage solution that runs on VMware ESXi hosts. You can use ONTAP Select Deploy to create and manage ONTAP Select clusters and nodes on the virtualized hardware3. References :- ONTAP Select two-node clusters with HA, SnapMirror Synchronous overview, Deploy an ONTAP Select cluster using the CLI.