Let me get the help you need to successfully import your bank transactions to QuickBooks Online (QBO).
One of the main reason why you're unable to import it to the program is due to the CSV file format. To help resolve this, let's check your template format if it's right. After that, try to import the file again and check to see if it works.
However, if you've encountered an error message during the process, I have some articles for troubleshooting steps to fix the problem: