When you follow a link found in the GW Libraries search, database list, etc., you will get the usual GW Single Sign-On (SSO) screen. You should not see a special OpenAthens sign-in screen.
If you are already signed in, you should be sent directly to the resource without having to sign in again.
For help with signing in, see GW IT's guide to using Single Sign-On.
OpenAthens allows you to use login links on many (but not all) sites.
Sometimes you may be asked to choose which GW library you are affiliated with. This may come from OpenAthens or from the GW Libraries search (Primo).