I have OS Sierra 10.2.15 and AE CC 2017 14.2 according to the splash screen. Here's my plug-in folder layout.
It doesn't seem to detect that the .plugin file is an after effects plugin either.. Are you certain that it is properly extracted from the .zip archive? Also are you certain that your version is not actually "10.12.15"?
I will have to set up my virtual OSX on my new system so it might take some time to recreate this issue on my end unfortunately;;;