The App Catalog has four components on macOS:
Catalog Agent, responsible for installing and updating apps: /usr/local/bin/catalog. This symlink points to /Applications/Catalog.app/Contents/Resources/Catalog Agent.app/Contents/MacOS/Catalog Agent
Catalog App, allowing users to install or update applications. This app also includes an admin mode to allow administrators to get app information such as the Bundle Identifier, description and Code Requirement: /Applications/Catalog.app
Catalog Notifications, responsible for sending persistent user notifications such as update reminders, upcoming enforcements and more. Catalog Notifications is embedded in Catalog.app: /Applications/Catalog.app/Contents/Resources/Catalog Notifications.app
Privileged Helper Tool, used by the Catalog App to elevate privileges so end users don't need administrator privileges to install or update applications: /Library/PrivilegedHelperTools/nl.root3.catalog.helper