Hi Paul, The “会译” plugin is launched for mainland China users, so you need to use WeChat to log in. You can try to install our overseas version Noam, which supports Google login and the interface is closer to the overseas style!
HomePage: https://noam.tools/
Add-ons Site: https://addons.mozilla.org/en-US/firefox/addon/noam-translate-assistant/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search