Welcome to the forum, @lorenzostucchi! When you get a chance, please introduce yourself here. I'd also encourage you to add a real picture as your avatar because it helps build community.
The Aggregate AWS instructions were a bit out of date and we just updated them. It may take a few hours for it to show up on the website, but can you revisit https://docs.opendatakit.org/aggregate-aws/ and give it another try?
You'll know you have the correct instructions if you see something like this:
