Your download will begin automatically. If it didn't start, download manually.
Open the .dmg file in your Downloads folder
Drag the Lubo icon to your Applications folder
Launch Lubo from Applications
Lubo is not notarized
It isn't signed with a paid Apple Developer account, so Gatekeeper may block it on first launch.
Right-click the app and select Open, or go to System Settings → Privacy & Security and click Open Anyway.