
to how to copy
You said, you can access the files

How?
Share? Just don't Run Calibre against a share. Copy to a Local drive, then run

Pop the drive out and put it in a USB caddy for the drive type.
Use as A Calibre Portable (way better speed than a Flash drive) or as spare or backup drive
Just because you install "portable", does not prevent Desktop Calibre from using the Library on Portable