If you want users to log in to your Joomla site using their Amazon credentials, you can simply do it using our Joomla Amazon OAuth plugin. Once you configure the Amazon with the Joomla OAuth plugin, you can allow Amazon users to SSO into your Joomla site using Amazon.
Similarly, you can map your Joomla roles based on your Amazon attributes/groups. To know more about other features we provide in Joomla OAuth plugin, you can download it by click here.