I tried several free and not-free plugins to get a 2-factor authentication, but this too did not work at all. So far, I got something only from “miniorange-2-factor-authentication”. Sometimes, while testing different plugins of this kind, I even ended locked out my website with no chance to log in again. Luckly I was doing all testing on a staging website and I do recommend doing the same with these dangerous plugins (they either do not work at all – as this one – or lock you out). For the paid version of this type of plugin, I also do recommend a full try-before-buy testing, otherwise do forget about them.