Once installed VMWare vSphere Update Manager, it is time to configure plug-in on vSphere client (You can configure and manage VUM only using vsphere Desktop c# client and can't be configured using vSphere web client only compliance checking is possible). Installation is very straight, Click Plug-ins to open Manager, you will see VMware vSphere Update Manager Extension under Available Plug-ins, click Download and Install, which download the software and start installation
PART 3.1 : VMWARE VSPHERE UPDATE MANAGER INSTALLATION ON WINDOWS 2012 R2
PART 3.2 : VMWARE VSPHERE UPDATE MANAGER PLUG-IN INSTALLATION ON VSPHERE CLIENT
VMWARE VSPHERE UPDATE MANAGER (VUM) - IMPORTING ESXI ISO AND CREATE UPGRADE BASELINE
VMWARE VSPHERE UPDATE MANAGER (VUM) - UPGRADE ESXI OS
This step need to be done on every vsphere client once, few next click (require administrator access to install the same). and it will finish installation and status will be changed to Enabled, also there be new update manager tab will appear on vCenter objects.
If you are facing issue with enabling update manager plug-in below article will be helpful for troubleshooting.
THERE WAS ERROR CONNECTING VMWARE VSPHERE UPDATE MANAGER [VCENTER:443] DATABASE TEMPORARILY UNAVAILABLE OR HAS NETWORK PROBLEMS
Useful contents for upgradation
VMWARE VCENTER 6.5 UPGRADATION ERROR
UPGRADING FROM VMWARE VCENTER 6.0 TO 6.5 PROCEDURE AND VSPHERE HTML5 WEB CLIENT
VSPHERE UPDATE MANAGER 6.5 UPGRADE AND VSPHERE WEB CLIENT PLUG-IN INTEGRATION1
ADDING AND CONFIGURING VMWARE VSPHERE VCENTER SSO ACTIVE DIRECTORY AS LDAP SERVER