SSO in Office 365 ProPlus with SCA (Shared Computer Activation)

With Shared Computer Activation the user is always prompted for their username on first launch.

With Federated Authentication (SSO) it is possible to remove the requirement for them to enter their password and only require them to enter their username at which point the authentication dialog will redirect them to your federated sign on page which would automatically sign them in. If however a individual users first use on a machine occurs outside the network this would not happen as most federated authentication deployments present forms based authentication to all external off network devices. (Remote Desktop is generally still inside the network from a federated authentication perspective)

The SCA first time user experience is documented here: https://technet.microsoft.com/en-us/library/dn782860.aspx#How shared computer activation works for Office 365 ProPlus