Not receiving autogenerated password

I recently closed my aweber account in favor of Mailchimp. We only have free members, but keep our best content behind a wall that users must register to view. Somehow, during the change over, something got messed up and I’ve going over and over and over everything trying to figure out what was missed.

In an effort to make things easier, I figured it would be better to have the password auto-generated. Biggest problem is the nobody seems to be getting the passwords. What would cause this to happen? searching mailchimp support yields a big fat ZERO. Searching here yields the phone book, but nothing that’s useful. If anyone has any suggestions as to what might cause this, please let me know. Thanks.