I am attempting to try out AutoCAD 2014 for Mac on my 2011 Macbook Pro (OS X 10.9.4). I successfully downloaded the installer package and selected "Free Trial" rather than entering in a product key. However, when I go to open the program, it produces a prompt that I must enter in the product key and serial number. What is the problem? Is there a product key and serial number that can be used to activate a free trial?