When you download a program there is a text under the download progress bar (A few important notes about our free software:) saying You may need to create a new User ID and Password to obtain a product activation code.)
What is meant with that? Where do I change my user ID? Is the chance bigger that I can get a serial if I change user ID or what?
The product activation website (http://autodesk.com/register) is separate from the Education Community. Therefore, you'll need to create a new Autodesk ID (via the "Create User ID Now" link right above the login box on that page) in order to sign in and activate your software. This step can be confusing, hence the messaging present on the Education Community.