I just purchased Lightroom 6 but it won't install, apparently since my computer is 32 bit Windows 10 Pro. What can I do? Do I have to use Lightroom 5 instead?
You'd have to purchase LR 5, if you haven't previously purchased it.
In my opinion, you'd be better off seeing if you can install Windows 10 64bit on your computer. You might have to pay for that too, I don't know.