The plugin is provided as a zip archive you can find at Plugins & Apps inside our platform. It can be unpacked anywhere on your computer. When you have unpacked the package, add it to your Unity project as follows:
Open the Package manager in Unity.
Select “Add package from disk…”
Select the package.json file inside of the unpacked package.
If everything went correct, the package should now be visible under the Packages list in the project panel.
If you decide to place the package inside your project’s Assets folder, it is important to still also add the package to Unity’s package manager. If you don't do this, the dependencies will not be loaded correctly.