Thanks for your first post, @hello-greenleave. I've made research about the error message you've received and found out that this error happens when your web browser interprets the HTTP response content as text/xml instead of text/html.
To resolve this issue, you'll need to ensure that the HTTP request URL, as you see in the browser's address bar, matches the <url-pattern> of the FacesServlet as registered in the web app's web.xml.
Hence, I'd recommend you go to your bank's website. Log in from there and copy the URL, then enter your bank's URL into the search field on the QuickBooks Banking page.
There are also times a financial institution chooses to only release one website for connection to QuickBooks Online despite having multiple bank names or different types of accounts.
You can check out Step 2: Try other listed versions of your bank's name outlined in this help article: Find your bank or credit card account when you connect to online banking.
For future reference, you'll want to keep this article in case you'll encounter specific errors when connecting your bank: Open Banking connection errors.
Feel free to comment below if you have additional questions. I'll be here to help some more. Take care.