All I have is a serial number. Customer service wouldn't help me because it is CS5, not CS6. I was given a link to the cloud to download the software. I downloaded, but it will not accept my serial number so I just wasted everything because my "free trial" started and I don't have time to use it right now. I was just trying to get the software installed on the new computer because the old one doesn't work anymore.
Download the trial version from http://prodesigntools.com/all-adobe-cs5-direct-download-links.html
Follow the Very Important Instructions on that page first BEFORE you click the download link.
Install the trial and enter your serial number to license it.