Can you be more specific about the symptoms? What version of Mac operating system are you currently using?
I am running High Sierra. I completed my taxes in March but always file late. Turbotax ran just fine. When I attempted to access my return it automatically updated itself and it no longer works.
You should have had to enter the License Code after you installed the program to activate it.
Turbo Tax asks for the License Code each time you start
I have never heard of that happening on a Mac. You had to enter a license code to originally install TT 2019. Did you switch user accounts on the Mac?
You might need to uninstall and reinstall.
Corruption could have occurred in the Application or in an associated preference or support file.
The best remedy is to totally uninstall TurboTax and all associate files and then re-install. That will not delete or change any .tax2019 data file that had already been created with the tax data.
To uninstall the application and all associated files need to be deleted and then the application reinstalled. If there was a state then the state must also be reinstalled.
Here is a FAQ for how to uninstall Mac
Also if present remove: ~Library/Caches/KSCrash/TurboTax