Works for me too (syr.edu), once I figured it out Rated 5 out of 5 stars
I had this plug-in for weeks and made many attempts to make it work. One thing that kept me going is all the positive reviews here of people being successful with making their Exchange working. (Well, and perhaps strong dislike for Outlook software.)
So if you are on Syracuse University email @syr.edu domain, than you need to FIRST (!) create an IMAP account in your Thunderbird and make sure that is working fine. Then you need to follow instruction on the plug-in support page. Finally what you need (and I was missing out on for weeks) is to know the domain. For SU it is exchange.syr.edu so the final line would look like this https://exchange%2Esyr%2Eedu%5C[your_username_here]@auto/
After (!) the set up is complete and I have my new but yet empty calendar in Lightning, Thunderbird asks for password again, and I remove the username that's there and put in [myusername]@syr.edu and than password. It asks it several times. I haven't figured out why, but it works: I can see my web/exchange calendar and make online modifications to it.
next thing is to get contacts synced :-/