Why am I getting an error stating "All invited users are already invited or have an existing account in Zoho" while trying to add a new user?
Whenever a user signs up for such applications, an org will be created. Consider the org as an internal space that will be created to manage all applications managed by the user. Like many other Zoho applications, Zoho Vault follows the org-model as well. At any given time, users cannot be a part of two or more orgs.
If the user already has a Zoho Vault account, uses other such org-based Zoho products, or has an active account in a different data center, they will be unable to join your organization's Vault account without deleting their existing org.
Learn how to delete your account.