This error message is displayed when using the download with more than three devices. You can use the download with up to two devices per account.
For more information about how to manage the device connection from [Download Management], please refer to this article: [Smartphone/Tablet] How do I delete a device from the downloaded devices list?
For more information about how to manage the device connection from [Download Management], please refer to this article: [Smartphone/Tablet] How do I delete a device from the downloaded devices list?