Please just upgrade to NVDA 2021.3.1, the most current release.

There were problems with updating both NVDA itself and NVDA Add-Ons during the 2021.1 and 2021.2 era that have all been resolved in 2021.3 and later.

If he really wants 2021.2, then still install 2021.3.1, uninstall it, and then install 2021.2.  The thing that gets fixed, that is causing the problem, is external to NVDA itself and once 2021.3 or later has been installed the issue vanishes even if you go back to an earlier release that was balking at installing.
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Brian - Windows 10, 64-Bit, Version 21H2, Build 19044  

The instinctive need to be the member of a closely-knit group fighting for common ideals may grow so strong that it becomes inessential what these ideals are.

       ~ Konrad Lorenz (1903-1989)