I just installed this for the first time and it does not do what it says, I have the same issue as another reviewer, there is no "Add to Firefox" button, instead there is just a button that says "Available on Chrome" which if I click redirects me to download Chrome.
I am running Firefox 50.1.0 on Mac OS X in case the operating system matters, but I don't think it should matter for this sort of extension that doesn't interact with anything else on the OS. Anyway I hope you get it fixed soon, I gave 5 stars since someone else reported the issue and you replied and said you'd fix it so I am trusting you to fix it. Thanks.
Edit: a little over a week later, now running Firefox 51.0.1 on the same computer, now it works flawlessly, I have no idea what happened, I did not change any settings. I was not in private mode, but I do have Do Not Track requests turned on. Some of my other extensions may have interfered, I don't know, anyway it appears to work fine now. I just used it to install a signed version of a Chrome extension in Firefox (one called FindFlix) and it works perfectly.
Thank you Rich for this review! We found the problem. Are you using private mode? Or in a new private window? This was causing the issue in my tests. Please see and if you have an account please discuss with me here - https://github.com/Noitidart/Chrome-Store-Foxified/issues/36