OK, I finally made it!
I have an external HDD where I put flightgear... And I installed HD scenery from the official site.
All scenery data was located on "Documents" folder (in the C: drive)
I create a folder called "FG Scenery" and I put all contents of Documents folder inside of it
I set up in the launcher a custom path to the scenery "E:\FG Scenery"
I tried to put something in the world and then pressed the key "D".
Now it displays properly a path in the console.
Many thanks for the help. I
REALLY appreciate that.