Hello Chris,
Thank you for reaching out.
It appears that the user you provided lacks sufficient access rights. First, please ensure that a valid license and email are entered under Page Builder Settings -> Update & License. Then, clear both the Joomla cache and your browser cache, and try again.
If the issue persists, please disable HTTP headers by going to System -> Extensions.
You can also try reinstalling the Joomla core. Just make sure to have a backup before proceeding.
Please let me know if this resolves the issue.
Best regards,