This feature allows you to access the plugin over your multiple subsites in a WordPress Multisite environment.
There could be two ways to use the plugin on the Multisite environment:
Use the same configuration on all the subsites
In this you need to install the multisite version of the plugin at the network level. The settings that will be configured at the network level will be applied to all the subsites. However you can disable the subsites where you don't want the SSO. Here is the screenshot for plugin configuration which will allow you to enable the sso on your different subsites.
Use different configuration on each subsite
Here you need to install the single site version of the plugin at each subsite. The settings configured will be specific to each of the subsites.