Calibre has a fixed structure -- Library/Author/Title -- for its libraries.
See this section of the User Manual ==>>
Why doesn’t calibre let me store books in my own folder structure?
And this sticky thread at the top of this sub-forum ==>>
Want to change folder structure or file names in the Calibre library?
You probably need to use the Save to Disk tool to copy books to KoboCloud - but don't put your library there, see -->>
I am getting errors with my calibre library on a networked drive/NAS?
BR