Contextual filter doesn't work with the name of the entity reference, it only works with its ID
Like Drupal 7 this configuration should work for you :

But for some reason it doesn't work, so your alternative is Views Taxonomy Term Name Depth module if you are working with Drupal 8.6 or higher version:``


Install and enable the module.
Add contextual filter Content: Has taxonomy term name with Depth

Save your changes.