SSO Server provides a single-sign-on architecture to integrate all your web applications. You simply need to add SSO server client scripts to original login page of all your web applications. When users log into any one of your web applications with their username/password, they will not need to type their credentials again to access other web applications.
Also, SSO client feature has been integrated into DSM. Please go to Control Panel > Domain/LDAP > SSO Client to configure DSM SSO settings.