In some situations, you might see this error Cannot enable delta analysis: Access Denied, followed by the message that you need additional permissions and Edit subscription when configuring PR integration with Azure.
It means that you don't have the required permissions on Azure: Subscription is webhooks and your token doesn’t have permission to add webhooks. In other words, you need to be in the Project Administrators group.
The solution is to update your permissions to make them appropriate for the needed actions, and then do the usual process of enabling PR integration.