I've got you covered on how to link your bank account to QuickBooks Online (QBO).
We'll need to search for your bank and try other versions of your financial institution that are listed. Just follow Steps 1 and 2 in this article: Find your bank or credit card account when you connect to online banking. If the same thing happens, we can request support for your bank since you can't connect your bank account and you try all the options matching your bank's name (still not on the list). Let me guide you on how:
Go to Transactions, then select Banktransactions (Take me there).
Click Connect account.
Search for the name of your financial institution. If QuickBooks is unable to find your bank, select 'Still can't find your bank?'. You may need to scroll down the page to find this.
Enter your Bank name and Bank web address (URL) in the field provided, then press Request.
Also, I'd recommend reconciling your accounts every month. This is to effectively monitor your income and expenses, and detect any possible errors. For the step-by-step guide, refer to this article: Reconcile an account in QuickBooks Online.
Let me know how it goes in the comments below. If you have other banking concerns or inquiries about managing your transactions in QBO, I'm just around to help. Take care always.