After the failures reported in this thread I borrowed an installation USB from a friend. I tried running setup.exe as both normal user and administrator, in each of the 2 user profiles on the 8.1 laptop. The result was the same: Nothing happened. To be more precise, when I tried running it as admin, the initial Windows 10 splash screen came up, THEN it silently failed. No error messagers, no new processes or apps listed in Task Manger, no nothing.
I am still able to install other apps from USB, so it's not a broad issue, it's specific to Windows 10. any suggestions, please?