Look at usage below.
To use this, install it through the package manager.
You can click on the code button in the top right, copy that or just copy this
git@github.com:dropecho/unity_animation_importer.git
Open unity, and open the package manager, in the dropdown select install from git, and paste that in.
It should then show up in the list of installed packages
There are two ways this is used, on initial import, the animations within the defined base path are setup using the settings found in the project settings menu.
You can then later, click the button in the project settings menu to re-apply all settings to the animations that have been imported / fall under the path chosen.
The "base avatar" is a animation that is used for the avatar for all other animations in the given path.
When using mixamo I would recommend downloading the t-pose and using that in the root of the chosen path dir. Otherwise, just choose the "rig/model" that represents the rig used for the creation of all the animations in the folder.