What is the linkage between datafeed and AWS s3?

I am considering using Analytics in the future.
I found out about linking data feeds by looking at the following URL,
I am not sure where to find the user ARN provided by Adobe.
Is it something that can be easily found on the datafeed screen?

We are considering using this service after knowing those steps if possible.

If anyone knows, please respond.
Thank you.

https://experienceleague.adobe.com/docs/analytics/export/analytics-data-feed/create-feed.html