You can still use the online version of TurboTax to file an amended 2016 return, as long as you do so before October 15.

If you prefer to have the desktop version loaded on your Mac, you can get a downloadable copy at the web site below, or you can buy it at a store. You can buy the least expensive version; the program will unlock other parts only if you need them.

https://turbotax.intuit.com/personal-taxes/cd-download/