This article explains various scenarios with SSO and email login
The implementation of Workspace offers the workspace admins a choice to enable the login process for the members with SSO, Email or both. This setting can be setup and enabled from Manage Workspace >> Security >> Single Signon Settings.
The landing page of any workspace will initially show only the public communities to the members. Once a member logs in, they will gain access to both private and public communities available to them.
Login Scenarios:
1. Workspace with only Email login: In workspaces offering only email login, members with access to private and public communities will see only the email login option.
The workspace admin can configure the SSO login settings from Manage Workspace >> Security >> Single Signon Settings. 
If the workspace admin wants to provide members with the option to log in using both Email and SSO, they must enable the Ideascale Email/Password login setting which will be visible to the workspace admin once the SSO setting is enabled in Workspace >> Security settings.
Once these two settings are enabled the login page will display both the options to the members for login.
3. Workspace with SSO login only: The members of the workspace with only SSO login will only have the option of SSO when they are at the login page.
The community admin can also choose to have a selected group of members be able to login via Ideascale Email by setting the group in Community Access Rules settings.
Members of private communities can only log in using the workspace URL, while members of public communities can access the login directly through the community landing page URL. If both SSO and Email login options are enabled, members from either community—private or public—will have the flexibility to choose either login method.
4. Workspace login via SSO with Private community: Members must log in using SSO if the community admin has configured the private community to require it. Even if they see the option to continue with email, they will be logged into the Workspace. However, upon accessing the Private community, they will be prompted to log in via SSO.
5. Community Login via SSO or Email with Public Community: Members of the public community will be able to login using the SSO credential or the Email login as both the option is enabled by the admin in the community access rule.
