When setting up connection and trying to authenticate with Zitadel IdP, the redirect_uri parameter in the authentication URL is set to http://localhost:5300, which according to the documentation, is only valid for development mode and when SSL is not enabled.
This results in an error page from Zitadel:
{"error":"invalid_request","error_description":"The requested redirect_uri is missing in the client configuration. If you have any questions, you may contact the administrator of the application."}