How to Install URP or Universal Render Pipeline in Unity

 

Installing URP

1. In Unity, open your Project.
2. In the top navigation bar, select Window > Package Manager to open the Package Manager window.
3. Select the All tab. This tab displays the list of available packages for the version of Unity that you are currently running.
4. Select Universal RP from the list of packages.
5. In the botoom right corner of the Package Manager window, select Install. Unity installs URP directly into your Project.

Source:

https://docs.unity3d.com/Packages/com.unity.render-pipelines.universal@7.1/manual/InstallURPIntoAProject.html

How to Install PolyBrush in Unity

 In Unity Hub, 

1) go to Window > Package Manager 

2) Make sure "Packages" is on Unity Registry see image below

3) On the right side Search for PolyBrush see image below then click install on the lower right