The password emails are sent from support@cyberstart.com, unlike the CSA program welcome emails, which are sent from hello@cyberstartamerica.org - if you're using a school email address, it could be that your school is allowing emails from @cyberstartamerica.org, but blocking emails from the @cyberstart.com domain.

Here are two other articles for you to read that you may need to check.

I'm not receiving emails from CyberStart

What domains need to be whitelisted? 

If you have any further questions, then please contact our support team on support@cyberstartamerica.org and we can help you further.