I'm running Windows 11 on a stout computer. I installed 20.0.590 (because I use V-Ray, and that's the latest version it runs on as of now) and it works fine except Labs won't install. I clicked "automatically install" and it didn't, and when I click the "update" button the Labs shelf nothing happens. (I updated to 20.0.625, but, again, V-Ray doesn't run on it yet, and it crashes on startup, which is another thread.)

Resolution: Just had to re-install it two more times (!), that fixed it. The secret: give up hope, curse a bit, and then try one last time.