After installing the plugin, you should see a bunch of loader elements under 'Visual Elements' in the Bubble app editor.
Drag the loader you wish to use into your app, resize, and position how you'd like it. Customize the colors as well to your liking.
Then, you can leverage workflows to show and hide the element based on longer running operations in your app!
If you're having any problems, shoot me a message here:
https://forum.bubble.is/u/yla/summary