I downloaded the dmg file, and I tried to open it, a progress bar show up and disappeared.
Afterwards I found the etcher file in the device section, so I tried to open it and it says “balenaEtcher 1.5.15” can’t be opened because the original item can’t be found."
You should be able to get Etcher from https://www.balena.io/etcher/ .
Click on the “Download for macOS” button.
Open the downloaded dmg file, drag and drop the “balenaEtcher” icon onto “Applications”.
A “balenaEtcher” icon should appear in your dock.
Quote: "FAQ:
Can I use Etcher on Windows, Linux or Mac?
Etcher works on Microsoft Windows 10 and later, Linux (most distros) and macOS 10.10 (Yosemite) and later. Make sure you download the correct version from our downloads section."
However trying to run Etcher in 10.13.6 gives message “10.15 or higher needed”