How to Install and Enable the Geophilic Data Pack in Your World
Getting the Pack Into Your World
Geophilic is a data pack, not a mod, so it does not go in your mods folder. Place the .zip file you downloaded into the datapacks folder inside your world save. You can reach this by opening your world folder (found under saves in your Minecraft directory) and dropping the zip directly into the datapacks subfolder. Do not unzip it.
Activating It
If the world is already open, run /reload in chat. Then run /datapack list to confirm Geophilic appears and is enabled. If it shows as disabled, run /datapack enable "file/geophilic". For a brand-new world, the pack loads automatically as long as it sits in the datapacks folder before you generate terrain.
Important World-Gen Note
Geophilic only changes terrain that has not been generated yet. Existing chunks you have already explored will keep their old vanilla layout. To see the new fallen trees, boulders, stumps, and clearings, travel into unexplored chunks. If you want the full effect from the start, create a fresh world with the pack already installed. You can verify it is working by flying into new terrain and looking for the subtle additions like moss patches and bush clusters that vanilla does not place.