Automatic upload to lightroom

Hi,

I do not yet fully understand the way the Lightroom app functions. I'm on a small personal account and when activating the app and adding pictures. The app apparently uploads some files to the cloud. I'm not particularly interested in this. So I'd like to understand the following:

- Are those files still stored locally on my phone?

- What happens when my storage is full?

- Can I prevent the uploading from happening? And solely have the pictures on my phone?

Thanks