Casual vacancy of the auditor

Dear Members, Pls guide on the issue of filling ADT-3 in GNL-2 as the GNL-2 to be filled by the Auditor, it is not giving option for auditor certification . The Digital Signature Certification filed for the Directors & KMP are only displayed. Pls guide on the issue of filling ADT-3. Moreover can the  Appointment letter be issued to Auditor and ADT-1 can be filled by the Company before the approval of shareholders in the EOGM.