The "Global Scenery" is the foundational terrain data that allows you to fly anywhere on Earth. Without it, the simulator typically restricts flight to a single demo area (usually Seattle).
Because the base game crack was only 8 GB. Distributing the full 90 GB game was bandwidth-heavy. So, they released the "Base Game" and the "Global Scenery DLC" as two separate torrent magnet links. X Plane 11 Global Scenery DLC-CODEX