Asset Store
Quick Start
The process of downloading an asset from the Unity asset store is as follows:
Visit the asset store at https://assetstore.unity.com/
Sign In
On the asset page that you want to download click the Add to My Assets button and accept the agreement.
In the unity editor. Go to Window > Package Manager
In the Packages dropdown select My Assets. Then search for the asset you downloaded.
Once you have selected your package click Download (Appears only you do not have the assets downloaded already) and then click Import.
Select whatever assets from the package you need. By default Unity selects all assets for download.