I found a repository that was Forked from the original plugin.
Vincent Loi created it! And is working fine in Android Studio 3.6.1! (and with Android studio 4.1.1)
Here is the repo android-drawable-importer-intellij-plugin
And here you can download the plugin.
Note from Vincent Loi:
This fork came about because the original package stopped working somewhere around Android Studio 3.5.
I have provided an installation zip here. As at 31Jan2020 it is known to run nicely on AS 3.6 RC 1. Any feedback would be appreciated.