4K slideshow Maker won't work on Mac OS El Capitan

Hello - I experimented with 4K Slideshow maker a while ago, and loved what I saw, but when I tried to start making some shows, I found that the program will not work. It does not allow me to add photos, and neither way works (drag and drop or selecting files from file menu). I am using El Capitan and have downloaded the latest version. (1.6.1.938)

I also tried using Mac OS Lion (10.7), but the program said it would not work with that older system.

The program does not give me any indication that there is a problem, but nothing happens when I try to bring photos in.