You can create multiple clients in Cognito User Pool. Usually, a client represents one application, no matter it is backend application or frontend application. When integrated with Alexa, the Alexa could be considered as a client. If you followed Build Device Binding UI, you should already have a Cognito User Pool in AWS Console. By default, the previous step has create two App Clients. Let’s create another one for Alexa .
Open Cognito User Pool Console, choose the user pool created for you
On the left navigation bar，select App clients
Under App clients，choose Add another app client
alexa in App client name
keep all the rest defaults and click Create app client