Download your platform's build after checkout. The macOS .dmg runs an installer that puts the AU, VST3, LV2 and the AAX for Pro Tools in the system plug-in folders; on Windows and Linux, unzip and drop the bundle into your VST3 / LV2 folder (Pro Tools on Windows: the separate AAX zip goes into Common Files\Avid\Audio\Plug-Ins). Rescan plugins in your DAW and load Focus on a stereo bus. It will not appear on mono tracks, by design. The macOS build is Developer ID signed and notarized; the Windows builds are signed too.