Password reset links are valid for 1 hour. If yours has expired, return to the Login screen, tap "Forgot Password" again, and request a new link.
This means you're not logged in (or your session has expired). Log in with your email and password. If you don't remember your password, use the forgot-password flow.
If problems persist after trying all steps above, email info@astrodiac.app with your account email address and a description of what's happening.