All Macs use Keychain. Completely behind the scenes, unless you yourself open and use the app.
Apparently two things are true:
Intuit Turbotax uses keychain;
Intuit has still done nothing in response to this, their serious design-mistake-or-bug.
When the box pops up, enter your MAC user password* click Always Allow.
You need to do this only one time. There is no other way to work around this serious error.
* When you started your machine and selected a user account, macOS asked you for a password. That is the password to enter in the field.
