Did you already purchase your ticket online? Just go to the kiosk at the Greyhound station and enter the confirmation number. It will print out your ticket. Or log in to the Greyhound app on your phone. If you use the app, you need to check in with the app 2 hours before departure, and then just show the QR code to the driver. No ID required.
Don't have a ticket yet? Just go to the counter and buy one with your debit card.