You will have received an email from CDbaby (after each submission) with a link included... you need to click that link and go through the steps in order to redeem.
As these links (which are converted into credits later by us) are issued by CDBaby themselves, they are not something we control or resend. If you did not receive this link after your purchase, CDbaby themselves will be the only ones who can assist/verify your submission qualifies and ultimately reissue the link.
Submissions made before the marketing campaign went live, will not be eligible. A prerequisite for the link to work is, is your Rotor account has to be affiliated with CDbaby (you need to sign up to Rotor through their CDbaby).
No affiliation = broken link (and credits cannot be added)