You will need to contact Customer Support to discuss changing to the online version. Turbo Tax for Mac 2017 download requires Mac OS 10.11 or later. Please see the instructions below for contacting Support. They are available 7 days a week from 5:00 AM to 9:00 PM PST.
https://ttlc.intuit.com/replies/3300041
Related Information re: Mac requirements CD Download and Online
https://turbotax.intuit.com/personal-taxes/online/deluxe.jsp
https://ttlc.intuit.com/replies/3299949
