Error "User with that email already exists" while registering the user in User Management.
A user may fail to be added if they have previously registered. This is quite common.
If the user you are attempting to register is already affiliated, the user themselves must contact their current administrator and request to be removed from their affiliated account, and the current Administrator has to delete the user from their account's User Management. Affiliated users have access to their administrator list via their profile page.
The above steps need to be actioned by the user due to the data protection/GDPR law.
If you receive an error when attempting to remove the user, make sure the user is not designated as a Fulfilment Contact first, then remove the user. For more information, see this article.
Once the user is removed from the old account, you will be able to add the user.
When adding the user, you may receive an error message "This user already exists. Click 'Add to account' to add to your account.". For resolution, please follow the steps in this article.
In rare situations, there may not be currently any Administrators on the account, to which the user is affiliated. In such a case, please Contact us or log a Service Request on the Service Request Manager for assistance.
How do I find my Administrator?
"This user already exists. Click 'Add to account' to add to your account." message when adding a user