After importing the package you can find all 3D models in the folder 'Assets/Visual Design Cafe/Stylized Nature - Grasslands' under a sub-folder with the name of your render pipeline. The models are created as prefabs and are separated by category in subfolders: Flowers, Grass, Rocks, Shrubs, Trees, and Vegetation.
If you want to use or modify any Materials, Textures, Shaders, or other source assets then you can find those in the '(Source Assets)' subfolder.
A demo scene with an overview of all assets can be found in the 'Assets/Visual Design Cafe/Stylized Nature - Grasslands Demo' folder.