A staff member cannot sign in

Which field to use, and who cannot use the app at all.

Staff sign in with one field — a phone number, an email address, or a staff ID. Any of the three works, as long as it matches what is on their record.

If they are told to use the web instead

Admins and Bursars work in the web console, not the app. That is deliberate rather than a fault — the work they do does not fit on a phone.

A forgotten password

They can reset it themselves from the sign-in screen. An admin can also check the account is still active — a staff member who has been deactivated cannot sign in, and will not be told why beyond being refused.