Unfortunately, there are no alerts available to notify users once they are enrolled into a credential. However, you may set up an alert to go out a certain amount of days before the expiration date of the credential as a way to notify them instead.
Another way to make sure your user is reminded of their enrollment into a credential is to pin a credential. Pinning a credential will ensure that it will remain on the top of each of your user's Schedule. For more information on how to pin a credential, click here.