User accounts that are configured with Single-Sign-On via SAML cannot schedule CDA Application Workflows to start at a future date or time.
At the time of scheduling for a future date, a password prompt in CDA pops up and the password won't be accepted since the original authentication for the credentials happens on the identity provider side and not at the CDA or Automation Engine side.
Release : 10.X, 12.X, 21
Component : Automic Workload Automation - Continuous Delivery Automation
The functionality was never implemented in CDA, SSO SAML user is unable to schedule workflows in the future with 'Starts At'.
Normal Automation Engine user should be utilized instead in order to schedule deployments in the future.
Vote on an enhancement request below if you would like for this functionality to be implemented: