Adding Ionic to an already existing Angular project

Hey all , I’m new to Ionic and entered the following based on the docs :
ng add @ionic/angular
it says : For adding Ionic to an already existing Angular project, use the Angular CLI’s ng add feature.

now my app does not render and only shows a listing directory with the src directory as empty. I thought by adding this it would allow me to expand on my existing app . Would someone advise me on this Thanks