As said you will only need one VUM.
sarkmo wrote:
But you can create a Windows VM and install VUM there, then install a plugin(?) to integrate it into VCSA. How does this work exactly?
During VUM installation it will ask you for the IP/Hostname and credentials for your vCenter. It will then automaticly install the VUM extension on the vCenter.
When you connect to the vCenter with your C# vSpere client, you can install the client plugin from Plug-Ins -> manage plug-ins. (The C# client is still needed to configure patch-baselines etc.)
Tim