AFAIK, the download wasn't available until this week. If you have the public beta version installed, you can't use that to license; you need to uninstall the public beta version and then download the GM version.
I'm not sure about this for Education, but have you checked in your AdobeID account info if the order and serial number are present? Go to the upper right of this page and sign in. Then go to My Products and the serial number should be present if you registered a fulfilled order.
I hope you ordered your product from the Adobe store direct because you will have the least problems then. Contacting Customer Service is the way to go with such problems.
Cl54321 hasn't said he/she bought Photoshop CS6.
Perhaps he/she bought Photoshop CS5.1 with a student discount in April and is awaiting approval. If that's the case, cl54321, and you don't find your serial number at the My Adobe link, you should call Adobe customer support to ask the status.
Also, you should know that if you bought CS5.1 in Aprill you should be eligible for a free upgrade to Photoshop CS6, so once approval is received you should pursue getting an upgrade serial number for that as well.