If you’ve created an account on Tin Can using Google log in, meaning that you clicked the Google button and signed up using your Google Account, you would need to use the same method to log in again. Click the Google button in the middle of the screen and log into the account you signed up with through Google.
If you’ve created an account using Email, meaning that you clicked the “Sign Up with Email” button, you would need to sign in with the Email Address you’ve signed up with. Click the “Already have an account? Sign In” on the bottom and log in using your Email Address.