The link below will show you how to use your prepayment code. Alternately, at the bottom of that page is a link for "Where can I find my Installation Key?" if you were sent an IKC via email for the downloaded version of the software.
In the online edition of TurboTax, how do I use a prepayment code? -
https://turbotax.community.intuit.ca/replies/2648021
