External IDP not working for End-user authentication: No dynamic_metadata found

New to Istio here. I’m running a bare metal k8s cluster with Istio 1.2.5. I’m trying to use my own IDP for end user authentication but seems not working. Checking the envoy log it always says “No dynamic_metadata found for filter jwt-auth”.

How are the requests after the IDP sending along the token, in a header or in a url parameter?