Sits and spins on "checking for updates". Zero movement in over an hour. Fairly useless. Running on El Capitan and Parallels 11.1.3 (32521). Now what? Just forget it and run Bootcamp? VM Fusionware? Keep running Windows 7? There's absolutely no help in the Parallels support that I can find, anyway.
I had to open CMD and type net stop wuauserv and then net start wuauserv to get it past the "checking for updates" bottleneck. Surprised that in all your install notes there's no real troubleshooting info.