Unity doesn't reliably accept "promised file" drops from web browsers, so the cleanest path is a tiny Editor script that browses AssetVault from inside Unity and one-click-imports any asset into your selected Project folder.
- Click Download AssetVaultWindow.cs.
- Drop it into your Unity project under
Assets/Editor/ (create the folder if it doesn't exist).
- In Unity, open
Window › AssetVault Browser.
- Select the Project folder you want assets to land in, then click Import on any row.
One-time per Unity project. The script remembers your AssetVault URL via EditorPrefs.