You can login when prompted after using a link from a library page. If you are not already using Blueline / Office365, you will be prompted to login with your NetID@creighton.edu / password and then verify with Duo.
Some vendors have added links to OpenAthens on their site. If the libraries have paid for access you will be able to login beginning at the vendor's site. Different vendors may use different links/logos or steps to get to OpenAthens.