Obtain a client with either the client_secret_basic or client_secret_post authentication methods selected and save the secret. You will need to use it to authenticate requests to the OIDC.

Employ an IDP URL specific to your service's geographic region and run IDP discovery. This step will retrieve the authorization and token endpoints, available scopes and other essential components needed for the standard OAuth flow.

EU: https://login.klarna.com
NA: https://login.klarna.com/na/lp/idp

Follow the rest of the OAuth flow according to the standard https://datatracker.ietf.org/doc/html/rfc6749.