To generate, view, update, and cancel E-Way Bills on GST Zen, you must allow GSP API access in the Government E-Way Bill Portal.
Log in into the Government Portal www.ewaybillgst.gov.in with your username and password. On the left hand side, find the menu item called Registration. Click on Through GSP. Add a new GSP enter your username and password. Save the details.
GST Zen can now generate E-Way Bills for you. Provide your username and password while generating your first E-Way Bill.