To import into your scene go to File>Append, navigate to .blend files folder, open the file, open "Group" folder, then double-click on the name of the group and append.

Or you can select it and copy it using CTRL+C and in your scene pressing CTRL+V.

Please note that this scene contains textures from Alexander Happy - Textures may not be redistributed

HDRI maps are from HDRI Haven

contains plane with particle system which you can use for easier workflow - f.e. linking particle systems or adding directly to your scene

If you are working in Eevee please note, that model was created for 2,79 Cycles and need to be adjusted to work in Eevee (Alpha change to Alpha hashed in the material option)