With Cusmin, you can apply customizations to the Login page or even to the public pages. These customizations will be visible to everyone, even visitors that are not registered users with the WordPress site.
However, it is possible to share the same configuration with another set of users, so if you apply it to e.g. Editors, you can use other settings in this configuration to change admin panel, like admin bar and admin menu settings. This way you will use the same configuration for public pages, and admin-panel facing settings will be applied to Editors.
It is possible to use only one PFC configuration at a time, so all other configurations (even though you set any Login page / public site settings inside of them) will not be applied. This can be useful if you want to have multiple customizations for these pages in different configurations, and to switch between them with this option, if you want to.
In this example, Login page / site pages settings from the Default configuration will be applied.