After you register an account, you must check your email and click to link verify. We need you verify to make sure that is real email to restrict spam. If you dont see the email activation, please check in Junk Mails too.
Other case, you actived account but still can not login. Please make sure you submited correct email + password. If you enter wrong more than 3 times, your account will be locked. Then try again after 15 minutes or let us know.