Step 1:

Visit the EA security page: https://myaccount.ea.com/cp-ui/security/index

Step 2:
Log in and click Security.

Step 3:
Click View Backup Codes to see your codes.

Step 4:
Copy backup codes 1, 2, 3, 4, 5, and 6 and use them when placing your order.
If any codes are already used, you can generate new ones using the provided button.