You should have received an email with your username/password to your official education/organization email address. This email is sent out when your curator (professor/administrator) adds you as a player.
If you are a curator this email is sent when a NICE Challenge Admin makes your account.
If you believe you should have received an email and cannot find it first please try and reset your password with the reset password form by entering your official education/organization email address in the reset password form.
If that does not work please create a support ticket so we can look into it for you.