The error is caused by something on your network blocking the download.
If you are at work, university, college, or school, ask your IT Administrator as they may be able to remove whatever is blocking the download so it will work.
If this is not possible, please try connecting to a different Wi-Fi network connection to make the download. If you can connect to a different network (or mobile hotspot) you should find you don't experience the same issue.
If you are still having difficulty please contact our support team. Please quote the error message when doing so.