@Madhu Rao Thanks for your question. From the error provided, it seems you haven't registered Microsoft.PolicyInsights resource provider for your subscription. Also, you don't seem to have necessary permissions to register the resource provider.
I would suggest you check if the Microsoft.PolicyInsights resource provider is registered or not by traversing to subscriptions - > Settings -> Resource Providers -> Search for resource provider -> Select and click on Register.
Also, you must have permission to do the
/register/action operation for the resource provider. The permission is included in the Contributor and Owner roles. Kindly make sure you have necessary permissions.