Get Fog Volume 3 from Asset Store: https://www.assetstore.unity3d.com/en/#!/content/81802

Please note this integration component is work in progress!

Unpack the .rar archive and add the Enviro FogVolume Integration component to one of your gameobjects in your scene and assign your FogVolume - Clouds and Fog object. You also can leave it unassigned if you only want to use clouds or fog. You can add the component through unity component menu:
"Enviro" -> "Integration" -> "Fog Volume 3 Integration"