The following images display the flow of configuration screens after selecting create new user pool from the AWS Cognito User Pools console. The changes and selections are identified by the red arrows. These settings will support use of the new User Pool by the lex-web-ui.
Once the user pool has been created, the pool's app client settings also need to be configured.
An app domain name for the User Pool also needs to be specified.
Finally the Identity Pool needs to be configured to utilize the new Cognito User Pool as the authentication provider.