I'll take it as this is a new bank connection, useramanda-dolce.
I recommend validating the bank credentials first on your financial institution's website. Once verified, try connecting bank account again on your QuickBooks Online account by following the steps below:
- From the Transactions tab, select Banking.
- Click Connect account.
- Enter or select your bank.
- Enter the sign-in info you use for your bank's website.
- When you're ready, select Sign-in.
Once connected, you can now categorise the transactions. I've added these links for more information:
I want to make sure everything is taken care of for you, please let me know how it goes or if you have any other issues or concerns.