Login issues can be caused by a number of things. The most common cause is an incorrect password. The second most common cause is an incorrect or unregistered email or username. Another potential cause is an account where the email was entered incorrectly in the first place, meaning that when that email is used in future, it doesn't exist.
Reset Your Password
The number one solution is to try resetting your password. You can do that via this page: https://www.teachstarter.com/password-reset/
If you are still having difficulty logging in, please contact us and we will look into the issue right away.