Dillard's Credit Card (by AmEx) (Q Mac)

My wife has a Dillard's credit card issued through American Express. When I attempt to add the credit card to my Quicken accounts (Mac), it fails. I use the login and password that is used on the website Dillard's Card Services which I know is valid. I have also tried to log into the AMEX website with the credentials from the Dillard's Card Services site but they are not recognized.