You can use the GUI installer to perform an interactive upgrade of a vCenter Server appliance 6.5 or 6.7 in a High Availability (HA) cluster that uses an embedded vCenter Single Sign-On or Platform Services Controller to vCenter Server appliance 7.0. You must run the GUI upgrade from a Windows, Linux, or Macintosh computer that is in the same network as the appliance that you want to upgrade.
You can deploy version 7.0 of the vCenter Server appliance on hosts that are running ESXi 6.5 or later and on vCenter Server instances 6.5 or later.
A vCenter HA cluster consists of three vCenter Server appliances that act as Active, Passive, and Witness nodes. The Active vCenter HA node is upgraded using a migration-based upgrade while preserving the existing configuration.