To anyone having issues downloading from nintendozone.no-ip.org, it's been reported as an attack site for some reason, so your browser and/or antivirus are likely blocking it. In Firefox, go into Options, and on the Security tab, uncheck the "Block reported attack sites" and "Block reported web forgeries". You might want to re-enable those once you're done, though. I believe most antivirus programs have an option somewhere to disable them for a brief period of time. Avast has it if you right-click the Notification Area icon, under "Avast Shields Control".
If you have an antivirus, it's likely going to flag nzone.exe as a false positive, causing it to delete the program even after you've downloaded it, as well as block it from downloading the list of MAC addresses. You can add the folder you download it to as an exception for your antivirus, so once you have the .macs file, you should be okay to have your antivirus running and still be able to use the program.
Hope this helps people.