This plugin is designed and developed for use with WP OAuth Server (https://wordpress.org/plugins/oauth2-provider/). Once Single Sign On Client is installed, it will add Single Sign On abilities to used another WordPress sites users. Use Case Site A is your main WordPress site but you need to launch another WordPress website or service (Site B). Instead of having all your users create a new account on the new website, you can simply use Sign Sign on from Site A.