Ensure that users are available on Advanced Authentication server and AWS account of your organization.
Navigate to AWS SSO > Dashboard.
Copy the User portal URL under Settings summary.
Navigate to the User portal URL in a browser and check whether you are redirected to Advanced Authentication login page.
Complete the authentication as per the chains configured in the SAML event.
For example, specify the user credentials in Username and Password if Password Only chain is available.
Check whether you can access the Single Sign-On page.