... But mere mortals running Vista SP2 32-bit are, once again , excluded from even trying to run that application on their Vista copy...
If you had tried on (regular) Windows XP SP3 32-bit with lowering the subsystem version in the PE header to 5.1 (it's set to 6.0 by default), I guess a similar error, pertaining to win32 apps, is to be expected, as the application is NOT win32, compiled to be only runnable in the 64-bit architecture...
What I can see , based on your attached screengrab, is that the app was compiled using version 5.9.7 of the Qt Framework, which in itself provokes major surprise on yours truly... ; I have always known, and that knowledge is based on official Qt documentation, that the last Vista-compatible version of the framework was 5.6 (5.6.3 to be exact!), and only on client machines :
https://doc.qt.io/archives/qt-5.6/supported-platforms.html
... whereas v5.9 of Qt has zero support for Vista (and, of course, XP):
https://doc.qt.io/qt-5.9/supported-platforms.html
Any explanation as to how a Qt 5.9 built application is able to launch under Vista SP2 64-bit is highly welcome (if somebody can provide one ) ...
For official system requirements, see @win32 's post; so, your assumption is not correct, as Vista (64-bit only) isn't officially supported! Given that the PE-header in the main executable is set at a subsys version of 6.0, at least our beloved OS was taken into consideration in that regard, but who can say which NT version the actual build-time compiler optimisations were targeting? As detailed above, I remain quite sceptical this is indeed running under Vista SP2 64-bit...
OT: I hope you all had a great Xmas Day, surrounded by your loved ones; best wishes for the New Year, too!