You cannot use the desktop (CD/download) on a Chromebook. A Chromebook does not meet the system requirements. So.....you must be using online TurboTax without realizing it. You cannot pay for online TT using that license code. You will need to seek a refund for the CD/download that you cannot use. And...you will have to pay the fee to TurboTax for using online.
Not sure if TurboTax will give you a refund for the software purchased from Amazon or if you have to pursue it with Amazon.
Try TT and see if they will:
To request a refund from TT ; https://support.turbotax.intuit.com/forms/refund-request.jsp