The TurboTax 2017 desktop editions require use of Mac OS X v10.11 or later (64-bit required)
See this TurboTax support FAQ for Mac minimum system requirements - https://ttlc.intuit.com/questions/1899173-minimum-system-requirements-for-turbotax-mac-software
If you are not going to upgrade your OS then you can get a refund of the software purchase by contacting TurboTax support.
Go to this website to contact support during business hours - https://support.turbotax.intuit.com/contact/
Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax
You can still use the TurboTax 2017 online editions at this website - https://turbotax.intuit.com/personal-taxes/online/
