It's a free benefit of your ATB Financial Mastercard, and some online merchants require you to have it. If that's the case, you will be asked to to enter your SecureCode before your online transaction is completed.
If you haven’t already signed up for your SecureCode, you will be asked to do so during the checkout process. Then you'll be able to proceed with your purchase.
Or you can prepare by getting your SecureCode now.
Sign up for Mastercard SecureCode