The latest and greatest version of OpenShot Video Editor for Linux, Mac, and Windows can be downloaded fromm the official download page at https://www.openshot.org/download/.
Most Linux distributions have a version of OpenShot in their software repositories, so installation should be easy. Some might have an outdated version though (make sure to check the version number). The easiest way to ensure you have the very latest version, is to download an AppImage from the project website. Once downloaded, right click on the AppImage file, choose Properties, and mark the file as Executable. Now, go ahead and double click the AppImage to launch it.
Download the DMG file from the project website, double click it, and then drag the OpenShot application icon into your Applications shortcut. This is very similar to how most other Mac applications are installed. Now launch OpenShot from Launchpad.