I assume you are referring to the new
KT-3?
Support for that was added in the latest version of calibre (v2.62.0) You will need to run a modern version of calibre.

Alternatively, you could download the source code for that calibre release, add
this patch then follow the directions to set up a development environment:
https://manual.calibre-ebook.com/develop.html
...
There isn't really any good solution for running very outdated operating systems.