You have received the error message that your e-mail address and / or your password is wrong?
In this case, please check if your e-mail address and password are spelled correctly. Sometimes, there are little typing errors. If you still can't log in with your user data, please request a new password.
You can request a new password in the app directly:
+ Tap in the app on "Login", the button on the right in the start window
+ Then tap on "Forgot password"
+ Here you enter your e-mail address and you'll receive an email with a link where you can enter a new password