Dear user,
If the original model was created with Forest Pack Pro, you will need almost a valid full license to show the objects and render. Render nodes don't need licenses, but you need almost a valid license in a workstation to summit a render job.
You can contact with your model's provider to ask for a scene with the forest converted to meshes, but due the dynamic nature of the plugin this process have limits. Is possible that the resulting scene will be too heavy to use, or animation or effects can't be preserved.