Fediverse

Everything they mentioned checks out, but keep in mind that every ham within line of sight to the station will be trying to get into the repeater as the ISS passes overhead. The number of people trying to talk could realistically be in the thousands when it passes over a large populated country. And a full pass at a good angle only takes 5 mins give-or-take.

People take turns, but it's usually just a rapid-fire of IDs, locations and maybe some very short pleasantries, then you get out. Anything more is could be considered bad etiquette, and calling the ISS is kind of a big deal! It's not possible to have a full conversation unless you're extremely lucky with timing and/or geography, or there's an astronaut working the radio who wants to chat. I have heard astronauts operating. Sometimes directing and acknowledging contacts sometimes they will have longer form chats, but they're not at the radio all the time.

It is really fucking cool, though, to be in say, New England and hear someone in Texas or Puerto Rico or Canadian Maritimes coming through on your dinky Chinese handheld! The "normal" operating range of these radios is well under 20 miles, so that's a huge part of the appeal of working a repeater in orbit.

Also, you can get the radio and start listening in before getting licensed, you will just not be permitted to transmit on the ham bands. That is how I started and I got hooked!