If you’re looking to track conversions for app downloads, your best bet is going to be to mark both links as conversions in Unbounce as Vlad had mentioned. This will mark each ‘download’ button click as a conversion in Unbounce. The only issue with this is that we aren’t able to see if the app was actually downloaded or not, so the conversion data might not be 100% accurate.
With that being said, it looks like Google Analytics has a way to track actual app downloads, which will be pretty valuable for being able to dig down and see what funnel your downloads are coming from. I haven’t actually used this myself, so I won’t be able to really dive into how this actually works, but you can find more information about that here:
Most of our customers choose to integrate with Google Analytics anyways, so adding this should be a natural extension of your analytics efforts in general.
Hope this helps!