Hi,
you can buy TurboTax desktop here: https://turbotax.intuit.com/personal-taxes/cd-download/
Please note that this is a separate purchase that anything you might have paid for on TurboTax online.
After your purchase, the download would be available
here: https://turbotax.intuit.com/commerce/account/secure/login.jsp?pagecontext=download
Let me know if you need further help.