I had to do this in Firefox as Chrome has been very hard on my host the last month or so (don't know why, it just crashes it).

1. Attempted to join meeting in Google Calendar.
2. Clicked Join meeting.
3. This took me to a new tab.
4. As I was doing this in Firefox, it took me to download a Debian package for my host. This downloaded and the tab said it would wait while I installed it. I did this:

   ~ $ cd Downloads/
   ~/Downloads $ sudo dpkg --install google-talkplugin_current_amd64.deb
   Selecting previously unselected package google-talkplugin.
   (Reading database ... 162346 files and directories currently installed.)
   Preparing to unpack google-talkplugin_current_amd64.deb ...
   Unpacking google-talkplugin (5.41.0.0-1) ...
   Setting up google-talkplugin (5.41.0.0-1) ...
   Processing triggers for mintsystem (7.9.3+1) ...
   

5. After a short time, it recognized it was installed and put the tab into a black mode. I saw a bubble saying, "Select 'Allow' for both Google Talk plugings in order to access the video call. See detailed instructions"
6. I clicked Allow in the upper right corner of the browser tab.
7. Then it gave me some other confirmation dialog that went away as I was clicking outside the browser.