New version 1.2 seems to have introduced this bug:
FATAL: The configured Unity3d installation directory (/Applications/Unity/Unity.app) is not recognized as a Unity3d home directory. Remember that the plugin adds per-platform suffixes and is searching for the executable at /Applications/Unity/Unity.app/Editor/Unity.
That is not the correct path to Unity executable on OSX. It is "/Applications/Unity/Unity.app/Contents/MacOS/Unity"