Have you ever received a red error box that reads, "Unable to add the user: This user is a member of another account. Please contact support for assistance." when trying to add collaborators to your subscription? If so, you have encountered a User Add-in Error (below).
The User Add-in Error pops up due to one of two reasons:
The member you have added already has a free guest account
Somebody else has already added the member to their subscription
To resolve, simply ask the member you wish to add to email firstname.lastname@example.org and provide consent in moving their account under your subscription. Our Support team will then assist you in completing this task.