Let's make sure to use the correct email address or login credentials, rtodd.
Any additional characters, punctuation, or letters on the email address can be the cause of the error. If it's correct, I'd recommend reaching out to our Phone Support team. An agent will take a look at your account and can link your email address with your QuickBooks account.
Click the Help icon, and then Contact Us.
Enter Link unused email address to QuickBooks Online account.