curl -L https://istio.io/downloadIstio | sh -

if installtion failed, please check if it is downloaded.

To confirm that the Bookinfo application is running, send a request to it by a curl command from some pod, for example from ratings:

 kubectl exec "$(kubectl get pod -l app=ratings -o jsonpath='{.items[0].metadata.name}')" -c ratings -- curl -sS productpage:9080/productpage | grep -o "<title>.*</title>"