I didn't think the v6 extension would work with the v5 app? (I need to use the v5 app as I need to sync with a ios device running ios 9.2 which is too old to run a v6 compatible version of the mobile app) I can give it a try though
Edit: just tried it, no luck unfortunately, I just get a error saying "Enpass Assistant is unable to connect with the Enpass app."