How to add a root bone to a character from Mixamo if plugin "Mixamo Rootbaker" isn't working?

How to add a root bone to a character from Mixamo if plugin “Mixamo Rootbaker” isn’t working.
Tutorial:

In this tutorial, it is shown as follows:


But for me, it doesn’t work and looks like this:
image

I usually find the hips and delete all its key frames,so it doesn’t move anymore.it’s a minute job. no need plugins.

I want the animations to work fully, just like the character’s skeleton.