For reasons that I can't guess, some people's software seems to be
treating this link:
http://www.columbia.edu/~em36/DOSBox-X-App.zip
as if it begins with "https:" and not "http:". It begins with "http:".
It does not begin with "https:". If you see your browser trying to
access "https://www. etc.", find the "s" and delete it and you can
download the file.