It looks like that’s a plugin. Currently plugins are not installable through FAB.
Since it’s ‘newly acquired’ I assume you purchased it just now through FAB? Do you see it in your Epic Games Vault? (EGS Launcher → UE Library → Vault)
Having the same issue. Some (not all) of my assets/plugins are not available to download or accessible in my Epic Launcher Vault. How can I access these assets? I am uninstalling the Epic Launcher and reinstalling to see if that somehow helps.