Even if the author gives you permission to download, build, and run the software, you might also need to buy a Qt license. AFAIK your choices for Qt are GPL or

Even if the author gives you permission to download, build, and run the software, you might also need to buy a Qt license. AFAIK your choices for Qt are GPL or the (fairly expensive) commercial license. Since the software isn’t under a GPL compatible license my understanding is that you may well be obligated to buy the commercial Qt license.