What action is necessary when using Azure NetApp Files to set up an NFSv4.1 application?

The necessary action when using Azure NetApp Files to set up an NFSv4.1 application is to register the subscription for the NetApp Resource Provider. Registering the NetApp Resource Provider is crucial because it allows your Azure subscription to utilize the Azure NetApp Files services. This registration is a foundational step that enables the provisioning and management of storage resources associated with Azure NetApp Files.

Once the resource provider is registered, you can proceed with further configurations, such as creating volumes and setting up export policies, but without registering the resource provider, you would not be able to access the necessary services and functionality that Azure NetApp Files offers.