This is not the correct command.
The “Correct 3D Drift” command is a script, not a plugin. Use File New Script if you want an editor into which you can paste, and subsequently save, script code.
That said, I am cutting a new 1.0.2 release of the Edit: The new
Correct_3D_Drift.jar right now, which I will then upload to the update site, so that you can receive it from the Updater as usual. I will edit this post once the release is complete and available.
Correct_3D_Drift version 1.0.2 has been released and uploaded!