When a new employee joins and register with the workforce system, they use their email address to log in. If this email address is subsequently added to the 'Manage Users' section and assigned a role, an error will occur, preventing the addition from being completed.

I suggest using a different email to add your employee and assign a role in the manage user section. Follow these steps how:

1. Go to the Gear icon and select Manage User.
2. Click Add User.
3. Provide the details and email address, then assign a role.
4. Hit Send Invite.

Additionally, you can visit this link to add, edit, and remove authorized access in QBO.

For future reference, click this link to change your company's primary admin user. To learn more about usage limitations in QBO, check out this article.

If you need further assistance or have any questions about managing your user, please feel free to leave a comment below. Take care.