There have been a number of issues lately with downloading the contest version of RMMZ. I've spoken with TouchFuzzy (of Komodo) and they while they investigating it constantly, they aren't completely sure what is causing the error. However, they want you to have access to a version of RMMZ to use for the contest.
So, if you cannot get the current download link to work, please do this:
1. Try a browser other than the one you normally use (so Chrome instead of Firefox, Brave instead of Sagari, etc.) If that DOES work, please reply here with (1) the browser your used that did not work, and (2) the browser you used that did work. That way we can continue to try and fix the issue.
2. Then, if you still cannot download the file, contact TouchFuzzy on the RPGMakerWeb Forums, RPGMakerWeb on Twitter, or me on Discord (Studio Blue is my handle). We'll get you a direct link to the contrst verison of the game engine.
Thanks for understanding and good luck game-making!
(EDITED for clarity...!)