Integrations Server on Elastic Cloud - Install Agent

I'm trying to monitoring Azure using Elastic Cloud.
I'm reading this doc:
Ingest logs, metrics, and uptime data with Elastic Agent | Observability Guide [8.1] | Elastic

But I don't understand how to install an agent in our platform.

We have these servers, one of them is an Integrations Server.

Trying to add this integration:

To finish it we need to add an agent:

How is this agent installed on the Integrations Server?