To me this setting (using same email address for personal account and business account) may cause trouble.
Please refer to Cause 2 and Resolution 2 in this link: "Someone has already set up Teams for your organization" error in Microsoft Teams
See if you can change the email address of the personal account.
And since this issue is more an account issue than a Teams usage issue, please consider contacting support via Microsoft 365 admin center>Support>New service request for better support.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.