Never buy stl files if it doesn't come with rhinoceros files, otherwise you will never be able to use the file you bought. The designer thinks only about the visual side. But he doesn't know and doesn't care about the technical side! I tried this on myself, I did not have an interview with the author, but this is a general phenomenon; They don't care about your problems after the purchase. I once tried to interview the author and he answered me with sarcasm. So it is not worth interviewing the author of this either. You just have to throw away the purchased file!!!!