My main goal is to ensure you can complete your tasks.
Beforehand, can you share more details about adding a credit card to the list of expenses? Do you want to add a new credit card account? Or are you trying to add a new credit card payment method? Or would you like to add them as an expense transaction? Sharing more info will help us provide accurate steps to accomplish this. A screenshot would be a great help, too.
Please don't hesitate to get back on this thread. I'll keep an eye on your response.