If you are attempting to import a brokerage statement 1099-B or dividend or interest statements (Forms 1099-DIV and 1099-INT), you will need to provide login information for your bank. This is strictly used to access your bank portal and is not remembered by TurboTax or used for any other purpose.
If you are uncomfortable with doing this, just scroll down the page to where you can see the button "I'll type it in myself" and click the button. TurboTax will bring up pages for you to enter your data manually.