Some products include installers while others need to be extracted straight into the sim's Community folder. The location of that folder depends on how you installed the simulator.
Please consider using Simstaller, for all your installations, then you won't need to read further.
* We don't recommend or support using on/off add-on management tools with our products. A direct install is ideal.
Microsoft Store version
%localAppData%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community
Steam version
%appData%\Microsoft Flight Simulator\Packages\Community
If your add-on doesn't appear installed, please consider using Simstaller or go down the path of further troubleshooting here: https://parallel42.com/blogs/wiki/my-sim-does-not-load-the-add-on-i-just-installed