The site supports 2-factor authentication using 2FAS Light plugin. It is free, open source and does not require an account with the author, and as far as I’m aware it does not call home.
Obviously, you need to be registered to use it. You can register here.
After logging in, you should land on your profile page.
Click 2FAS Light on the left hand menu.
Follow the 3 steps. If you don’t have a 2FA app yet, I strongly suggest you do NOT click the buttons for getting the mobile app. Instead, use Authy, avaible for Android, desktop, iOS, browser plugins, and even some smart watches and really is a better 2FA app than the others out there.