This worked for me on a MacBook Pro:
Go to keychain>passwords, For whatever reason I had many entries for TurboTax, so I had to go back a ways in time to find the right one. But look for an old installation date from the previous year that contains that long code that you might have seen in the error message. Click on that one to open, type in your regular password you use to unlock your Mac keychain, it asked me for the password twice. Then click on the Access Control tab in the small window.
Select previous year's app and remove it with the negative button. Then click on
“Allow all applications to access this item” and click Save Changes
Then when I went back to TurboTax, the error message went away and it worked fine. Good luck!
