Your registration attempt has been blocked. Reason: Already registered.

I receive this error after doing an upgrade from Joomla 4 to 5. I was able to repair databases but now I get this error when testing my registrations. 

I am attempting to set it up so that when a person registers, they are set to be automatically added to our Paid group, but it won't work if it won't allow me to register.

webtomixresearch.com/mnaged/index.php/registration

That's CB AntiSpam duplicate registration protection. You can disable it in CB AntiSpam > Parameters. If you had installed CB Quickstart then it would've been enabled by it by default as CB Quickstart applies high security settings. It's detecting your IP address already belongs to an account and is blocking the duplicate registration.

Thanks, solved that issue but now I am getting a new one.
Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser.

I have tried in Safari and Chrome and cookies are enabled on both browsers.

Thanks, solved that issue but now I am getting a new one.
Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser.

That would be the CSRF token failing. We don't control that anymore in CB and is entirely handled by Joomla. It often only fails due to Joomla page caching being enable. Do you have page cache enabled in System > Extensions > Plugins?

The Cache was turned on. I turned it off and now I get the cookies message when I put in an email into the registration form. 

Clear Joomla's cache and refresh the page then see if issue persists. If it does within CB > Field Management edit the "email" field and under Parameters > Validation set "Enable Email checker" to "No" as something on your site/server maybe blocking this functionality.