1) upgrade your computer system to meet the min standards https://ttlc.intuit.com/questions/1899173-turbotax-for-mac-minimum-system-requirements
2) use another computer that does meet the min requirements
3) use the ONLINE program and get a refund of the Downloaded version
Our Satisfaction Guaranteed (or Guaranteed Easy) policy says that if you're not satisfied with your TurboTax software, you can return it within 60 days of purchase for a full refund (see the Intuit Software End User License Agreement for the fine print, about 2/3 of the way down the page - Section B, Additional Terms and Conditions, point #6).
To submit a refund request online, simply fill out our TurboTax Refund Request Form.