Probably the same problem I had:
Your google play is linked to your cellular provider account by default (i.e. your phone bill). This has limits that the internet doesn't seem to know about (from my searching)
So: Go into the play store app, menu, payment methods. Add a credit or debit card. Then back to turbotax, try again but when you "buy" you have to select your credit/debit card as the payment method.