Silverbucket's instructions and documentation has moved to a new address:
https://manual.silverbucket.com
Single sign-on can be configured to use from system settings in admin panel.
(Admin -> System settings -> SSO Config)
Click "Setup" button on desired protocol to open configuration modal.
Fill out the form and click "Save".
After saving, the setup button turns green indicating that the SSO has been enabled with the given configurations.
More instructions on SSO configuration can be found on authentication provider documentations: