This environment is intended to host the automated CI / CD pipelines that support your application. For instructions on setting up and installing base software, check out the UAT Server Setup Guide. The UAT environment is intended for super users and testers of your application to identify and fix any functional defects in the application.
This environment is meant to be a replica of the production environment and is meant to catch any deployment related issues. This staging step can be redundant or unnecessary for smaller applications and becomes more necessary when multiple servers enter the infrastructure equation (e.g. separate SQL Server or load-balanced web servers).
The Production environement gosts the production instance of your application. For instructions on setting up this server, check out the Production Server Setup Guide.