After the required Sitecore package has been installed the site will need to be configured to use the new connectors against your Salesforce organization.
Configuration of the module requires making manual changes to the web.config, App_Config/ConnectionStrings.config, App_Config/Sitecore.config and App_Config/Security/Domains.config files. You also need to check a setting in the module configuration file which is App_Config/Modules/S4S/S4S.config (see Configuring Unique Key Property (Optional)).
S4S Release 2.911.19305.1 introduced changes to allow the Security Connector to work if the Sitecore Identity Server is also being used.
To enable the Security Connector, in the file, App_Config/Sitecore/Owin.Authentication/Sitecore.Owin.Authentication.config, place an additional entry in the <services> section
<configurator type="FuseIT.Sitecore.SalesforceSecurityProvider.Owin.Authentication.S4SServicesConfigurator, FuseIT.Sitecore.SalesforceSecurityProvider" />
This has to be after the default configurator.
Adding a New Salesforce Domain