Next you see every Orbit app that's out for the Mac, each one ticked. Untick any you don't want, then press Install.
Each app is downloaded from Orbit as it installs, so you get its newest release. Keep the Mac online until the installer finishes.
Every app is checked before it goes in your Applications folder: it has to be signed by Orbit and notarized by Apple. An app you already have is replaced by the newest release, keeping your data; if it's open, it closes for a moment and opens again on the new version.