import from hd to lrc

Unfortunately, your explanation seeems incomplete. "I can't add pictures to collections or delete them from the catalog" doesn't explain. Please tell us how you are trying to do this (step by step, in detail) and what exact word-for-word error messages (if any) you are getting.

This explanation should help you to remove photos from catalogue and collections https://jkost.com/blog/2019/05/removing-vs-deleting-images-in-lightroom-classic.html

Here is how to import photos https://helpx.adobe.com/au/lightroom-classic/how-to/import-photos.html