Almost always, this is a forgotten password, and it is quick to fix. Go to the Sign In page, click Lost your password, and enter the email you signed up with. We will send you an email with a link to set a new one.
If that email does not arrive within a few minutes, check your spam or junk folder, since it sometimes lands there. If you are sure you are using the right email and still cannot get in, contact us and we will help you sort it out.