If you are sure that you have entered your email correctly during registration and have checked the Spam of your email and you are sure that you have not received an email, contact the journal admin and report the email problem. (Contact us)
In the login page, select the option "forgot password" After entering your email, a new password will be sent to your email.
It is better to have only one profile in each publication and perform all your roles (author, reviewer, editor, etc.) with the same profile. If you have registered in the system several times, you can notify the journal admin to merge your profiles.
This message means that this username has already been used by another user and you should use another username to register. To get a new password, go to the "Login" section and select the "I forgot my password!" option.