I have already installed Unity on my PC.now I want to use Vuforia with Unity.But in new Vuforia site they don't provide us to download their SDK for already installed Unity.How can I download it.
Install the latest version of Unity, and in the Unity component selection section of the installer, select Vuforia Augmented Reality Support, along with either the iOS Build Support or Android Build Support packages.
Create a Vuforia developer account from the Vuforia registration page. This account gives you access to the tools you need to make AR and MR applications with Vuforia in Unity.
If you have not already created a Unity ID, then do so from the Unity registration page. You need a Unity ID to download any packages from the Unity Asset Store.
Open Unity and create a new 3D Project (make sure the 3D option is selected next to the Add Asset Package button). Name your Project, then click the Create project button.
To activate Vuforia in your Unity project, access the Player settings from Edit > Project Settings, then select the Player category, and select the tab for the mobile device you are building to. Under the XR Settings panel, enable the Vuforia Augmented Reality Support property.
From Unity Docs