Hi Alejandro,
It should show up if you search for the AMI ID, which is ami-da58aab3. That said, the easiest way to launch a galaxy cloud cluster if you're not already familiar with EC2 is probably using usegalaxy.org/cloudlaunch. This interface will guide you through the launch process without any extra input on your part other than providing your AWS keys.
galaxy-user@lists.galaxyproject.org