I didn't see any popup blocked message appeared. But I managed to get the token by clicking the gears button and click the key at the bottom

It doesn't work with Greasemonkey. You need to use Tampermonkey. Many other scripts on stackapps also don't work with Greasemonkey

@ᔕᖺᘎᕊ It seems the problem is due to Greasemonkey. I replaced it with Tampermonkey and now it's working fine. Probably that was the reason many of my scripts didn't work in FF. But I don't know why it asks To complete the SOX installation, you need to get an access token! Please press "OK" to continue and follow the instructions in the window that opens. every time I open a new page

I get 404 - Not Found at https://raw.githubusercontent.com/soscripted/sox/v2.2.0/sox.‌​enhanced_editor.js on FF. How can I fix it?