Based on our experiences, I'm guessing that "Allow Always" is the fix to get things working. And yes, the PW for iCloud Keychain is whatever you use to log into your computer. I think I recall that long ago and far away, this was a different and unique PW, which turned into the log in computer PW when Apple went to two factor authentication allowing your specific devices to serve as the second factor.
If "Always Allow" is really the solution, then I would classify this as a 'bug' in TurboTax, especially since there's no clue when it fails as to what's causing the problem. And... this has never been required in previous versions of TurboTax, but this could be caused by changes in Apple's OS and not caused by TurboTax.
