The terrain tool does't work.

Heya. It looks like you have the samples asset pack installed from the Asset Store. If you are looking for the Terrain Tools package that adds better brushes and utilities, you will want to search for it in the Package Manager. If it doesn't show up, you might have to enable Preview Packages in the Package Manager portion of your Project Settings or if you are on 2021+ you can click the + icon in Package Manager and add by name and type "com.unity.terrain-tools" and add the package that way.

 

here's how you can add it if you are on Unity 2020.x: https://forum.unity.com/threads/cant-find-terrain-tools-package.686488/#post-6317178