You first have to build a 64bit Qt with MinGW. This wiki article might help you get started.
Hope it helps
yes, specify 32 and 64 for msvc2015
i was able to ignore the warnings
the kits i picked worked
@yigene To add to @mrjj : does your app need that amount of memory? If not and it does not have memory leaks than there is no real reason to have it as 64bit.
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