When you first tap on "Publish", the first thing the Optimization Assistant will ask you to do is verify your email address.
Click on the corresponding orange arrow and it will take you to the right panel in your account settings.
You will be asked to 'Send a verification email' or to 'Set a different email'. (if you don't receive it, please check your spam box).
Once you click on the link inside your email, your email will be verified with your SimDif account.
Watch the tutorial video:
How To Confirm Your Email Address