I had no problem downloading the software after buying a CD at Costco. When I went through the steps, it placed a download link in my Online Intuit account. Do you have an Online account (required)? Did you follow the steps in the FAQ below? If so, where does it fail?
https://ttlc.intuit.com/community/installing/help/i-bought-the-cd-but-my-computer-doesn-t-have-a-cd-...
The instructions are also in the Costco packet on the cardboard CD holder where your code is displayed.
