AWS Cognito Client Application Setup
Setting up a Client Application
A client application, associated with the Cognito user pool, needs to be created and associated authorization flows need to be enabled in order for the secure information to synchronize with your Reach Engine.
To do this click App Integration under the Cognito User pool

Click Create app client

Setup the client with the appropriate AWS authentication flows
ALLOW_ADMIN_USER_PASSWORD_AUTH
ALLOW_CUSTOM_AUTH
ALLOW_REFRESH_TOKEN_AUTH
ALLOW_USER_PASSWORD_AUTH
ALLOW_USER_SRP_AUTH
Click save