The link to the NSMBU hack isn't dead, it still works for me.
Also, if you're browsing the forums on a mobile device (and you're trying to download the NSMBU hack there), URLs/links (in posts on the forums) are broken on mobile devices. So, you should go on your computer and try to download the NSMBU hack there.
If the link still doesn't work (even if you're on a computer), then it's an issue on your end (and I don't know how to help you).
Don't expect me to be very active here, since I have plans, and many other things in my life.