AVAY works in a browser with nothing to install. The apps add things a browser cannot do: proper camera and microphone permissions from your operating system, screen sharing, links that open the app directly, and updates.
Select Download in the left bar. It works out which computer you are using and offers the right file first.
Opening it anyway on macOS
Drag AVAY to your Applications folder first.
Open the Terminal app — press Command and Space, type Terminal, press Enter.
Paste this line exactly and press Enter: xattr -dr com.apple.quarantine /Applications/AVAY.app
Open AVAY normally. It will not ask again.
That command removes the “downloaded from the internet” mark from this one app. It changes nothing else on your computer.