Hi nicola burighel,
Sorry that you have to endure a problem.
Please check if the download was complete, the easiest way to see if there was a problem, check the file size, it should be 518.3MB. I had several connection interruptions, hence my tip. It typically stopped a quarter of the expected size.
Then, if the file is really complete, use an un-zip application. Sometimes the installed one will not work. If so I use the free un-zip (Stuffit) from this company.
On the right side is a Free app download.
Which I use since several decades by now, it just works.
Another option is to find a download manager for your browser, which allows for a re-start of your download, if the connection was interrupted.
However, in this case, I wasn’t able to get it either, so I will move this thread to the site issues. Please allow for a little delay, as most people have a day off, based on the Holidays here.
All the best