Where does one enter the total value of traditional IRAs at 12/31/2017, so the entire basis at 12/31/2016 is not subtracted using TurboTax Freedom Edition?

Click the Continue button on the Your 1099-R Entries page.  In the follow-up, indicate Yes, you made and tracked nondeductible contributions to your IRA.  After confirming your basis carried in from 2016, TurboTax should present the Tell Us The Value of Your Traditional IRA page where you can to enter your 2017 year-end balance and the amounts of any outstanding rollovers or recharacterizations.