Sounds like you want to use Facebook or Google to log in... but we don't use those anymore. After some friction ("but I closed my Facebook account!") this extra step has been removed on the Web.
Log into Rabbit with your email address / Rabbit username and password, and you'll be all set.
Pssst! Do you have a mobile device? You can still sign in with Facebook or Google on mobile. Be sure to add a real email address and password when prompted, so you can continue using Rabbit.