X‑Plane will auto‑detect the library. However, ensure your scenery_packs.ini file (inside Custom Scenery ) lists the library global airports but before custom airport sceneries that reference it. Example order:
: A massive collection of 3D models including buildings, vehicles, and plants. MisterX Library ar library xp11 verified
For a deep dive into the technical "why" and "how" of how libraries like AR_Library work within the simulator's engine, refer to the from Laminar Research. Source: X-Plane Developer Documentation X‑Plane will auto‑detect the library