Zack,
This custom skill exposes Home Assistant to Alexa, it does not expose Alexa to Home Assistant. Generally speaking, Amazon does not allow Alexa to share connected devices with third partys like Home Assistant. Whenever possible, it is usually best practice to integrate any devices you have diectly with Home Assistant. In cases where there is no integration for your device you may be able to quasi-integrate it using a workaround using helpers and the Alexa Media Player custom skill