Some educational licenses or workshop bundles occasionally include Alpha Trees Pro. Check if your university has a Blender Cloud or asset library subscription.
While a free beta version was historically available for testing, the current stable versions are distributed as Lite and Pro editions. Lite Edition Pro Edition Built-in Assets Automatic Scattering Camera Culling Yes (Real-time) Scatter5 Integration Alpha Trees Pro 2.3.3 for Blender Free Download
: These planes use an advanced material with five distinct maps (color, normal, shadow, mask, and translucency) to ensure they react convincingly to scene lighting. Alpha Trees Pro 2.3.3 for Blender Free Download