MZFinance.BadLogin.MacAppStore_message error when signing into Apple ID
Mavericks does not support asking for two-factor authentication. However, you don't need to disable two-factor authentication to log in to services which don't support it.


Attempt to log in as usual. You will receive an error message which may vary depending on the service and version of OS you are using.
Choose to allow the login on another device and note the code given.
Append the code to your password, then log in again.