Sadly---the fact that you do not have a U.S. based credit or debit card is a problem for you. That is the only form of payment you can use to purchase the download from TurboTax.
https://ttlc.intuit.com/community/payments/help/what-forms-of-payment-does-turbotax-online-accept/00...
We hear from some ex-pats that they have been able to visit a U.S. embassy or consulate location near them and purchase U.S. based reloadable Mastercards or Visas to use for such purposes.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**