It might have landed in your promotions folder (this is common for Gmail users), or spam/junk/clutter.
If for any reason you can’t find this, but you have received a welcome email from CyberStart America, you can go to https://play.cyberstart.com/sign-in, go to sign in with your email address, but use the “forgotten your password” function. This should allow you to set your password in the same way as the original email.
If you have any further issues, then please contact our support team on support@cyberstartamerica.org and we can help you further.