To install a bush mission you have to copy the mission folder into the community folder of Flight Simulator. If you do not know where to find your community folder follow the steps :
While running MSFS 2020 do the following:
- Go to Options / General
- Click on “Data” which you will find in the list on the left
- Go to “Rolling Cache Path” and click on path. A window appear with several folders.
- Open the folder “Packages” and “Community”
- Drop your bush mission folder in it.
- Restart Flight Simulator and your bush mission appear.