In case of export of goods, if all details were filed like port code, Shipping bill no. and date is mentioned in GSTR-1, GSTR-3B is filed for the month. Then the details gets transferred to ICE Gate portal and if it matches the refund is issued automatically and no application is required.
In case of export of services, refund application has to be filed online along with invoice and BRC or FIRC for realisation of sales in foreign currency