Register Windows Virtual Desktop provider with the subscription
The last step to prepare for your deployment is to authorize the Windows Virtual Desktop service provider to be used in your subscription.
Register the Microsoft.DesktopVirtualization provider
Sign in to the Azure portal.
Use the search box to find Subscriptions.
Select the subscription you want to use with Windows Desktop Virtualization.
Under Settings, select Resource provider.
In the filter box, search for and then select Microsoft.DesktopVirtualization.
It may take a minute for the status to change to Registered.