* permission denied" backoff=1.55420699

I am trying to integrate the K8s(gke) cluster with an external vault in which I am facing the permission denied issue, I am following the offical-doc.
I also tried using the curl command from the vault-agent-injector pod but getting the same issue,
KUBE_TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
curl -k --request POST --data ‘{“jwt”: "’"$KUBE_TOKEN"’", “role”: “example”}’ $HOST/v1/auth/kubernetes/login

Can Anyone please help me to understand where I am wrong or which token I should use to authenticate the auth/kubernetes/login?

Thank you.