We haven’t seen the unizip fail for any of the users before. Maybe the download got corrupted somehow. There is a rar here: https://sourceforge.net/projects/dexterindustriesraspbianflavor/files/?source=navbar. Can you try downloading that and if that does not work too, can you try downloading an image from the archive and see if that works for you. Do you have access to another system where you can try unzipping this.