Mac
The installation is traditional, double click on dmg file. In the window that appears, drag the Logfly icon to the Application icon.
Unable to start
Since High Sierra OS and more recent Mac OS versions, you will get an error message like this :
The application is not damaged or corrupted, it is only a security issue.
To be identified as an identified developer, you must register with the Apple Developer Service for an annual fee. Logfly is developed in the open source and free open access spirit for the pilot community.
Since High-Sierra or other versions of Mac OS X such as Ventura, Monterey, BigSur, Catalina or Mojave, the option to install applications from non-Apple certified developers has disappeared.
Solution
You will have to launch the Terminal and be connected as administrator. If it is your personal Mac, it will always be the case. Then you have to type the following code:
xattr -cr /Applications/logfly.app
This command adds Logfly to the exception list of the Gatekeeper integrated protection system.
Here is a complete tutorial on how to do it.