Hi, thanks for the reply!
According to Plugins in Unreal Engine | Unreal Engine 5.2 Documentation
my project should have a Plugins subdir; but it does not.
The Epic Game Launcher->Engine Versions->4.21.1 Engine->Installed Plugins lists Substance as being installed.
In my project, the Unreal Editor->Edit->Plugins lists Substance as installed and the enabled checkbox is ENABLED.
I’ve restarted Unreal Editor and Epic Games Launcher. I still do not have Substance materials.