If you see the message "User does not exist" when trying to add a user to your device, it means the user has not yet signed up for a Plugzio account.
Please ask them to sign up at my.plugz.io. Once they've created an account, you can add them as a user by entering the email address they used to register.
Related Article: Plugzio user - How to sign up for a Plugzio user account
Need help with anything else? Contact the Plugzio customer care team to have a chat with one of the specialists and discuss your concerns.