I downloaded Macaos Enterprise executable, but when I restarted it was no longer on my computer

When you get the dialog to download Macaos Enterprise please choose a directory to download Macaos Enterprise to. If you don't specify a directory and instead just run the executable, the file will be saved to a temporary folder on you system. Depending on the settings in the browser the file may be deleted when you close your browser, and thus you would need to follow the link received in your mail and download Macaos Enterprise again.