The VUM service is a tool that allows you to efficiently manage patches and updates for VM, hosts, and vApps that are installed in the virtual environment. In comparison to previous versions, VUM no longer requires the installation of an additional external Windows server. This is because, since vSphere 6.5, the Update Manager server and client components have become part of the vCSA.
VUM is installed during the vCSA installation, and it's enabled by default. VUM uses a PostgreSQL database that is bundled with the appliance to store its data. Although both vCenter Server and VUM share the same PostgreSQL database, they use a different database instance.
In vSphere 6.7, a Windows-based Update Manager 6.7 instance cannot be connected to vCSA 6.7 during the installation procedure because it will fail with an error.
If Update Manager doesn't have access to the internet...