Thanks KarDip.
I compared my setup with the online tutorial, and everything seems ok (see below). I'm using Apache Metron as the SIEM, and I have Apache NiFi listening on port 9122 and setup to send these events to my SIEM, but KSC doesn't even connect to it. I tested it with netcat to make sure, but no data arrives. KSC shows me an event just like the one in the article I linked (but in portuguese, screencap below). For completeness, my licenses are also pictured below.
Is there anything else I can check on my setup to diagnose the issue?