You can’t create an automation that turns Lutron’s “Smart Away” mode on or off. In the Lutron app this is listed as a scene, but it isn’t actually exposed as a scene in LEAP - it is really a ‘switch’, which is probably how it should also be exposed in Home Assistant.
I found another repo describing how different Smart Away is exposed compared to scenes: Add support to enable/disable Smart Away · Issue #78 · gurumitts/pylutron-caseta · GitHub
There’s already been a few posts in the forums of people pointing out this is missing.