Hello @ErnestoCarreras2,
Your ArcGIS Enterprise organization will likely need to be accessible over the internet so that the Power Automate servers can submit requests to your ArcGIS Servers REST endpoint. If your ArcGIS Enterprise organization is behind your firewall Power Automates servers will not be able to successfully submit a request.
If your organization is accessible over the internet I would probably suggest making the execution mode for your geoprocessing service Synchronous as that will make the HTTP request a lot easier. If you use Asynchronous you will need to send constant job status requests after making your initial request. Using Synchronous for the execution mode will mean you only need to send one HTTP request and the response will have your result.
I would also suggest before placing it in the HTTP connector using a program called Postman which is a web API debugging application to test making HTTP requests to your geoprocessing service. When you have the request set up and working there you can then set it up using the HTTP connector in Power Automate knowing where to put what parameters.
Thank you,
Zach