Hi ​@whayes, welcome to the Box Community! Please refer to the guides below to help address your concern about adding Managed Users.
 

1. For existing user with free personal account:
    

   • Option 1: Invite the user to your enterprise.
     When trying to add a new Managed User in the Admin Console, you may run into the following message after pressing Save: "1 user failed to be added".
      

     After receiving the initial error message "1 user failed to be added", ignore the error message and press the Save button again. Saving a second time will begin the invitation process.

     This will send the user an email invite as well as a message in their Box account that they've been invited to join your Box enterprise account. Once the user accepts the invite they will be rolled into the enterprise.

     • Check out: "1 user failed to be added" Message When Adding Managed User article to learn more.
        

   • Option 2: Change the email address on the individual account.
     Advise the individual user to change the primary email address associated with their personal account to another email that is not currently linked to any Box account.
     
     They should then set their company email as a secondary email and remove it afterward. This will free up the company email address, allowing the enterprise admin to add the user as a Managed User.

     • Instructions for the user:
       Click your initials in the upper right corner > go to Account Settings > click Link Personal Email
        

2. For existing user that’s already associated with another enterprise
    

   • Option 1: Ask the user to contact the admin and request the deletion of their account from the enterprise to release the associated email address.
     
     This option is applicable if the user no longer needs to be associated with that enterprise. Please ensure all necessary files are downloaded before the account is deleted.
      

   • Option 2: The admin can change the user’s email address to another one, then remove the email address with your company domain.
     
     This option is applicable if the user needs to remain part of the enterprise.
     
     Once the email is freed up, you can add the user as a Managed User under your enterprise.

If you encounter any issues with inviting or adding a Managed User, you may submit a ticket to our Product Support team for further assistance.

Have a great day!