All members will need to claim their account in the new USAT membership system.
You should have received an email from USA Triathlon inviting you to claim your new account that looks like this:
If not please check your spam folder for the email, you can also force the email to resend by using the Forgot Password? link at the bottom of the login screen. Enter your email address and you will see the screen below which means your claim account email from USA Triathlon has been resent.
Check for the claim account email and follow the instructions displayed once you click on the link!