I had some strange problems with Skype and Office 2016, too.

The solution was easy: Office 2016 (Professional Plus in my case) installed its own Skype for Business software, which block the execution of the 'SkypeForBusinessPlugin.msi'

When you open 'Apps & Features' and choose 'Modify' , you should see 'Skype for Business' in the list.

Skype for Business lets you host up to 250 people in online meetings, and it provides a. Are not covered by the site license and cannot download the SfB client. SfB meetings as 'guests' after they install the SfB WebApp, which is a free plug-in. See directions for installing the SfB Web App in SfB Instructions for Students.

Download who is on my wifi for mac os x 10.6.8. Once you removed that feature, you should be able to run the web plugin, that usually is deployed, when you open a meeting.

Maybe that link helps with getting the right installer:
Trouble installing the Skype for Business Web App plug-in?

Hope it helps ..