I created a Profile with a GitHub login, but saving a Snack only prompts for a username and password. There is no option to add a username and password to my existing profile.
We don’t have github auth set up on snack yet, but all accounts have a username and password.
Assuming this is you (https://expo.io/@gordonf) your username is gordonf. You’ll be able to reset your password by entering the email associated with your github profile at Reset Your Password — Expo.