I just tried downloading it from a Windows and a macOS computer using Firefox and Chrome. In all cases I can test and extract the archive both with Info-ZIP's unzip (that's what Linux servers use) and 7-Zip. I also tried with the built-in ZIP archive support in Windows File Explorer and Finder. I can extract the archive just fine.
At this point I'd recommend trying to use a live Linux USB stick, i.e. boot your computer through a USB stick that has a Linux distribution, such as Ubuntu Linux. Use it when connected to the network through a different ISP, ideally a consumer ISP, not a school or other organization. If you still get a problem I'd recommend using a different unarchiver to extract the ZIP file. I've tried the built-in features in Windows and macOS, as I said, as well as 7-Zip. You can even use our Akeeba eXtract Wizard (desktop) or Akeeba Kickstart (web) to extract that ZIP archive.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!