An email address can only be associated with one Perdoo account.
If the user you are trying to add already has their own account, the previous account must be deleted in order to link the same email address with the company account.
Contact our Support team via the in-app chat at the bottom-right of your screen, or email firstname.lastname@example.org from the account you want deleted, and we'll be happy to help.
💡 Pro tip: As a Superadmin, enable Domain Sign-Up to automatically grant access to users with email addresses with your domain to join without an invitation. You can do this via Configure > General > Access and Security tab > check the Domain Sign-up box.
* NOTE: It's not possible to merge information from one account into another account. Adding the user will not carry over the information associated with it.