Sign in with the email that was added to Firebase Authentication.
Troubleshooting tips
Make sure you are using the exact email created in Authentication.
If you get auth/user-not-found, the email is not registered (add user in Firebase Console → Authentication).
If you get auth/wrong-password, use the Forgot password button to reset it.
If you still see errors, check the browser console and the Firebase Authentication & Firestore rules.
Instructions to Mark Attendance:
Step1: Select a Saved Record. If the required record is not found, Select Day, Date and Subject.
Step2: Start taking attendance by ticking the boxes. If the Required Subject is not found then add the subject.
Step3(Important): Click "Save Attendance" to save the record.