Adding book to existing library

Good day

Here is my problem:

I have mounted a library of books I would like to have.

Once I get the book and want to place it in Calibre it opens a new book.

I can always copy the book into the Calibre library file, but then the book doesn't open automatically when I click on it. I have to go to the file to open it.

Is there a way to add the book for it to open automatically without creating another book?

Thank you.