I was just having the same problem. If you don't have your account connected with facebook, then the way to login would be to enter your email address as the username without the @email.com part. Then enter your password.
Same problem again...... Ready to close my account!!!! Can log into the Website with no issues. But Galaxy App/ Forget it! Same issue with the downloaded app on my new Lenovo Computer. App/ Forget it! Tried all the usual stuff. Redownload, change password....etc.
Not worth my efforts anymore! Pandora gets my money!