The first time you access Ripl, you'll be asked to create an account using your Facebook, AppleID or Google account (depending on whether you sign up using an iOS or Android device,) or email address and password. The Facebook login will use whatever Facebook account is currently signed in on your phone's mobile browser (Safari or Chrome). or your computer browser.
To log in to your account, tap "Log In" next to "Already have one" or "Connect with Facebook" in the mobile app.