Hello carolinekaye, the only way to install in firefox an unsigned add-on is to use(install) Firefox ESR version 45.x, or Developer Edition or Nightly firefox version.

definitely see : What are my options if I want to use an unsigned add-on?

i suggest the Firefox ESR version 45.x, but if you want to keep your current version and to open the esr version together with the current release/version of firefox, your 49 release, you need the portable firefox esr version.

thank you

Just to clarify, are you using Endnote, the product from Thomson Reuters:

http://endnote.com/

And you're looking for a Firefox add-on to send data to that tool?

I haven't tried it myself and judging from the reviews for the Endnote extension, it hasn't been working for several years: https://addons.mozilla.org/firefox/addon/endnote/reviews/

Maybe the Endnote user community has come up with something else in the meantime. I suggest asking your tutors how they are doing it.

The University of Manchester has a training session on this which I will now attend. All the signs look to me as though the extension is a current thing given the dates on various sites. I have my account set up and working with Thomson Reuters, I just need to be able to use it with Firefox because that is usually my browser of choice. The instructions given suggest that there is a way to override the Firefox ban. I'm not a particularly technical person, so when it didn't work and I was being sent round in circles - that's the time to ask someone! But thank you for taking the time to help me. I appreciate that.