here's the page link:

Apparently, dl is 7.07 gb, unpacked it's 15 gb.

Prior to the release, here is the manual:

CHANGELOG V3.0 (October 2019)

  • newest OSM data Oct 2019
  • many many new objects: different castle types, boat houses and house boats, bunker,historic ships, offshore platforms, retail buildings, farms, different roofs
  • thousands new residential buildings and houses
  • typical buildings in the Alps region
  • FlyAgis Vegetation (HD trees and forests) included, adapted to ortho sceneries
  • Forests splitted at motorways and railways
  • 3D vfr objects (330 objects actually)
  • now there are 7 layers, refer to page 6 for description
  • compatible to newest OpenSceneryX v4.2.0+ (thanks to Austin G.)