How to Install latest addon

You can download latest addon from here. https://github.com/Ericsson/exchangecalendar/archive/master.zip

You will be downloading file exchangecalendar-master.zip Unzip the file In exchangecalendar-master folder, select all the items,compress them as zip Rename the compressed .zip files to .xpi

Then it is xpi add-on which can be installed