If you encounter this error, it means you have already maxed out the 3 devices Syntorial can be installed and authorized on. 

To authorize a new computer or iPad, just de-authorize one from your list:

1. Go to your account dashboard https://account.audiblegenius.com/courses
2. Click the “Authorization” button in the Syntorial section
3. De-authorize the devices you are no longer using for Syntorial.