If you already paid for the Online version call in and they should put the Desktop download in your account with the 16 digit License Code. If you need to buy the program you will get the License Code with it.
To install the Desktop program you need a full Windows or Mac computer.
Window System Requirements
https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...
Mac System Requirements
https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...
