You can install the app on macOS 10.15 Catalina and newer.
There are two ways to get ClearVPN for your Mac. Firstly, you can download the .dmg file from here by clicking macOS. After the download is complete, follow the steps on your screen - find DMG in your Downloads folder and drag and drop ClearVPN to Applications.
Or you can also install ClearVPN from Mac App Store if you prefer it this way. Click here to open App Store and get ClearVPN.