It would be nice if Intuit made this information available. Customer service sucks! I've used them for 10 years, but am unable to talk to anyone. Good program, but useless if it can't be loaded. Really sloppy Customer care
If your older Mac does not meet the system requirements for the download and cannot be upgraded, then you can still use online TurboTax instead of the download. Seek a refund for the download --- you cannot use the license key to pay for online software.
To request a refund for a TT product