If you scrolled down another dozen lines, you would have found the link to their FTP server and their SourceForge page:
ftp://ftp.info-zip.org/pub/infozip/
http://sourceforge.net/projects/infozip/files/
EDIT: Step-by-step to get zip.exe file:
- Go to FTP server.
- Click on the system you need. Use "win32" folder for Windows.
- Click on the version of Zip that you need. Version 3.0 is the latest version. For 64-bit, select the x64 file.
- Download this zip file.
- Extract the zip file to the location of your choice.
- Extract the extracted zip file to the location of your choice.
- Use zip.exe as needed.