Rated 1 out of 5 stars

No longer compatible with Thunderbird 68.3.1! Edit: Nope, it doesn't. Here https://imgur.com/a/rydMlaZ

This review is for a previous version of the add-on (2.1.5). 

That's simply not true. Engmail 2.1.5 works fine with Thunderbird 68.x

Click on "Search for Updates" using the "wheel" icon, if no update is found, then download Enigmail from here and install it manually. It is really definitely compatible Thunderbird 68.3.1.