I wasn't playing for the last Siege, do these things work out where you need to specifically organize a group from somewhere online to have a chance? Or can you just join up with randos in your sessions Gathering Hub and it works out? I'm guessing there isn't a way to SOS into this?
No SOS... what Kulve had was, ideally, a full session of 16 people, and then each takes on the siege in groups of 4 together. However, you didn't have to do it this way and honestly, one group of 4 was usually good enough.
Just search for the monster in the "search online sessions" part. The good thing about the beginning though is that EVERYONE will be rubbish because we don't yet know how the siege mechanics work (fully). However, I do think it could be nice to have the first experience with pleasant ERA members! :-)