Ok here's what I'm picturing.
Suppose it's like a Great Depression. Followed by a big sudden ET reveal. The Good ETs actually want it to be sudden, to shock humanity into change. The Bad ETs want to acclimatize. It's happening faster than they would like, but if they expect the Good ETs to intervene this way, then better to push their own disclosure controlled narrative.
Now the good ETs don't want to pepper everything with careful psychological calibration. When they show up you're gonna see humans, greys, mantids, whatever. And they expect you to adjust rather than give you a nice soft transition - mirroring their values for truth, freedom. Not psyops, for the most part. So the bad ETs anticipating this, will have their own crew set up. Mostly human. The non-humans, even if better known, will still be clandestine behind the scenes. They will have a friendly cautious veneer, well calibrated with just enough cool. The good ETs, while high tech and ready to supply the masses, will not have an "image" there will be a lot of you see what you get. But their opportunity to step in is that they are undeniably the good guys because they will offer supplies like food, without conditions.
The Bad ETs on the other hand will try to do the same . . . but with a slight shift. Contracts. Waivers. All the things we are already accustom to in our society. We have been acclimatized to see the world through a lens where you can barely stand up and get dressed without needing to sign a waiver.
Ok so where does that leave us. A crisis that was partly planned, but partly accidental and escalated. Two sides step in, avoidant of behaving like the authoritarians, because humanity is already bitter about pretty much all authority. But one will clearly have an . . . order to them. The other side will probably be more straightforward. And if it's anything like what happened with Eisenhower, they don't want you to mix and match. Both sides will give you the ultimatum. You go with them or you go with the others. Not both.
The vote will be cast by where you accept your resources. And a very grave mistake can be made in the immediacy of a sandwich.
Onto the physical staging of it all. People will congregate to abandoned buildings (of which there will be plenty) and tents if they prefer to be near the ground (especially if it's warmer weather) and lakes (because you have more food / freshwater sources).
If there is an ET supply, they would probably pick convenient places where masses congregate. The good ETs will not look for "official military outposts" to register their detail. They will pick a park that looks reasonable, or a corner in clear cross streets - and they will supply. They won't have millions of interpreters and socialists standing by like the Bad ETs. They will have telepathy, or basic signs and signals. That's it.
Supply lines would pop up in spaces that have a recognizable decor or spot because with the internet likely down, all people can go by is a basic description and a trail to follow.
All speculation but it feels like the outcome from what Farsight describes