The latest release of xLights for Macintosh can be found at the following link: http://www.dankulp.com/xlights/ or by using the App Store application.
The link will redirect your browser to the App Store Preview, and will automatically launch the app bringing you to the xLights download page.
Search for "xlights" in the Apple App Store.
Download xLights by Clicking the "Get" button.
After Entering your Apple ID and password, Click the "Install" Button.
After installing, "xLights" will appear in the Dock
Download the 'Vamp Plugin Pack Installer' from https://code.soundsoftware.ac.uk/projects/vamp-plugin-pack
Double click the downloaded .dmg file and run the installer inside the dmg file. Restart xLight and the new timing track options to appear.