For certain Angular pages, you will only receive Real-User Monitoring if you complete one of the steps listed. Meaning that if you do not follow these steps, you may not see user actions for any webpages using the Angular framework.
Correct, depending on your angular instrumentation, the OneAgent may not be able to automatically inject the RUM JS tag into the application code.
You would need to toggle the 'AngularJS and Angular' framework support first, and then insert the snippets that are provided after enabling the toggle wherever necessary. Be sure to scroll down in Dynatrace and Save changes as well after enabling the framework support in the UI.