Let's review your Chart of Accounts to check if you've already created the same credit card account.
- Go to Accounting.
- Select Chart of Accounts.
- Find your credit card account.
But if you're adding it through the Transactions page, you'll have to review your list of accounts connected to the online banking first.
- Go to Transactions.
- Select Banking.
- Click the Bank and Credit Cards menu.
I'm adding a few references here for ideas in managing your account and transactions: QBO Self-Help.
Keep me posted in the comments if you have any other questions.