check botaniq_documentation.png
but the gist is:
1. unzip botaniq.zip
2. either put botaniq in your polygoniq folder (if you already have materialiq) or anywhere on your PC
3. install add-on botaniq_addon.py into Blender and set the path to the botaniq folder
4. now you can find trees to plant in the sidebar of the 3D view!
Have fun planting!