1. In your Unity project, go to Edit > Project Settings.

   

2. In the Project Settings window, select Package Manager.

In the Scoped Registries section, fill in the following fields:

• Name: package.openupm.com
• URL: https://package.openupm.com
• Scope(s): com.coffee.ui-particle
• Then, click Save to save the changes.

1. Open the Windows > Package Manager window.

1. In the opened window, change the Packages filter to My Registries.

1. Select the UI Particle asset and click Install to install it.

By following these steps, you can successfully install the UI Particle package.