Yes, even when SSO is enabled, new users still need to be created in Dialog first. The date you set for the invitation is the date from which the account becomes active and can be used. The user will then receive an invitation email to get started with Dialog.
The user does not need to register separately. After opening the invitation, they are taken to the Dialog login screen and can sign in with their SSO account. They will then be redirected into Dialog automatically.
The user does not need to register separately. After opening the invitation, they are taken to the Dialog login screen and can sign in with their SSO account. They will then be redirected into Dialog automatically.