User Configuration →
Administrative Templates →
Control Panel →
Personalization

Policy Set to Purpose
Enable screen saver Enabled Forces screensaver ON
Screen saver timeout Enabled → Set seconds (e.g. 600 = 10 mins) Locks after inactivity
Password protect the screen saver Enabled Requires password on wake
Force specific screen saver Enabled → Set to your .scr path (example: C:\Windows\System32\medieval.scr) Applies company screensaver
(Optional) Prevent changing screen saver Enabled