CSS App Errors

After login into CSS App with the IDP, user sees a KeyCloak page with a message: User with (email/ username) already exists.How do you want to continue?

Warning: You are not authorized to access this page” while accessing Business BCeID account.

Error message: “InvalidFedratedIdentityActionMessage” while login into CSS app using Business BCeID.

How can I resolve Pathfinder SSO login error in dev (Invalid parameter: redirect_uri)?