Can admin update time on behalf of staff incase of missed punch?

Yes, the admin has the authority to update the punch details on behalf of staff. He can do it from the web dashboard or user app by regularizing the time.
In web dashboard it can be done from the Home page > Select staff > click on the date that requires update > Update In/Out Time

From the user app, he can do it from
User App -> Other Actions -> Regularization ->. Manage Staff Regularization