Stackdriver adaoter for Istio manual installation

We have installed Istio manually on GKE cluster. We want to install/add istio stack driver adapter so that Istio metrics are available on Stack Driver monitoring Dashboard of GCP. I am not able to get the metrics despite add the CRD as mentioned in

git clone && cd installer helm template istio-telemetry/mixer-telemetry --execute=templates/stackdriver.yaml -f global.yaml --set mixer.adapters.stackdriver.enabled=true --namespace istio-system | kubectl apply -f -