Hi Asha,
Welcome to Box Community and glad to help!
You'll only get this error if the email address with an existing Box account has been invited to join a Business/Enteprise account. Can you ensure that the owner is sending the collaboration invite this way?
Please let us know how it goes.
Thanks for posting!
Hi! The owner says she is using that method, so we're hoping we could just completely delete my account so I can sign up and be added as a new user?