First, let’s make sure that your child’s device is supported.
Aura Parental Controls is available on iOS and Android devices running iOS 13+ and Android 9+.
Next, ensure that you’re going through the proper device linking flow. https://www.aura.com/help/how-do-i-set-up-aura-parental-controls
If you’re still unable to link your child’s device please reach out to support so we can understand the issue and provide a fix!