The "Authentication required" required dialog shown when doing a network request that requires user authentication while not being logged into MB is currently mostly useless.
When we handled authentication using username / password this dialog actually allowed users to enter their credentials.
With the update to using oauth this dialog became non-functional. It still shows an "Yes" / "No" choice to login or not, but there is no functionality behind it.
Picard should trigger the oauth auth flow when pressing "Yes".