You can download it online without anything special. The part you need to be concerned with is whether or not the number you see on the box is the serial number. You can install the trial version and use the serial number to activate it to full use. Here is a link that might help you out as far as identifying the serial number:
https://helpx.adobe.com/x-productkb/global/find-serial-number.html
(do not post your number online for anyone to see)
As far as downloading the software goes, here is a link to a page in the Adobe site:
http://helpx.adobe.com/x-productkb/policy-pricing/cs6-product-downloads.html
You can also download the trial version of the software thru the page linked below.
Be sure to follow the steps outlined in the Note: Very Important Instructions section on the download pages at this site or else the download will not work properly.
CS6: http://prodesigntools.com/adobe-cs6-direct-download-links.html