When you registered with ENGAGE, a verification email was sent to your email address. You must verify your account within 72 hours. However, sometimes the verification email goes into your spam. Check your inbox of the email you signed up with, for an email from email@example.com. You should find a verification email in there.
If there is no verification email, then you may have put the wrong email address into your registration. If that is the case, register with your correct email address.
If you cannot solve the problem using this method, you can contact Engage Support by email at firstname.lastname@example.org.