This is a test version of the LibraryThing Match plugin for use with calibre 6 when it is released. It will also work with current versions of calibre from 5.0 upwards.
See the calibre 6 / Qt6 thread for details:
https://www.mobileread.com/forums/sh...d.php?t=344064
This version of the plugin can be installed manually for testing purposes. Report any issues at the bottom of this thread.