How to install WEBm Plug-in Manually (unable to figure this out)

I need to export a WEBm file.  (A prior thread is still unanswered)

There is a 3rd party plug-in that allows this, but I don't seem to be able to figure out how to manually install it. 

• fnordware/AdobeWebM · GitHub
• (this is a thread posted by Adobe last year:  WebM export from Adobe Premiere Pro &... - Adobe Premiere Pro | Facebook)

1. I have a Mac, latest OS as well as updated Adobe CC. 
2. It says I should have a Plug-ins folder. 
   • I get as far as Common, and there is only a Dynamic Link folder. 
   • There is, however, a Plug-ins folder outside of the Common folder.
3. I tried to copy the bundle file into that Plug-ins folder, but it didn't work. 
   • also tried creating the folders Plug-ins
   • then 7.0
   • then MediaCore and dropped it in there, but still it didn't  work
   • Then I replaced 7.0 with CC, and it didn't work

(I'm not in the Users folder.  It's definitely the HD Library) 

Any help?

Here are the install instructions:

Installation: Copy the plug-in to the shared MediaCore directory:

Mac:      WebM Premiere.bundle -> /Library/Application Support/Adobe/Common/Plug-ins/7.0/MediaCore

Win:     WebM.prm -> C:\Program Files\Adobe\Common\Plug-ins\7.0\MediaCo

For older versions of Premiere, replace "7.0" with "CS6" or whateve

Usage:  When installed, you'll be able to import a .webm file into Premiere.

Go to File > Export > Media and choose WebM as the format to encode WebM video.

WebM should also appear as a supported format in Adobe Media Encoder.