On macOS, the Impacter sample is composed of a packaged game (ImpacterDemo.app), an Unreal Engine project and a Wwise project.
While launching the packaged sample is as simple as double-clicking on ImpacterDemo.app, because the archive is downloaded directly from the Internet, opening the Unreal Engine project will lead the macOS Gatekeeper module to block the Wwise integration libraries.
A one-time action is therefore required to allow the libraries to be loaded. This can be accomplished by heading to the System Preferences > Privacy & Security section and allowing each library as they get loading on first open of the project.
We are sorry for this inconvenience and are working to resolve this issue in a future release.