Hey Walt,
I have gone through this problem once before and had essentially given up with Affinity but it's become a business critical process in my workflow and again, for some reason, it fails to install. I've followed the instructions you outlined and they don't solve the issue.
How in the world Affinity won't work but Adobe products do befuddles me.
Not that it has anything to do with Affinity but now even Skylum's programs won't install and older versions won't load.
It would seem that there is something about the way Windows 10 does things that mucks many programs up.
In any case, my workaround has literally to use another computer where it did load but it's not my main workstation - a bit like borrowing the mechanic's old beater while your main everyday car's in the shop and unusable.
Does Affinity have a screen share support service? That would go a long way to not wasting time in forums.
Cheers,