Tone matters a lot here. There’s a huge difference between “You’re welcome to join these calls if you like, since it will impact how you work once you start” vs “We need you to be on these calls [with pushback/pressuring if you don't want to]”. This sounds like the latter, which is definitely not “being kind”.
> “We need you to be on these calls [with pushback/pressuring if you don't want to]”.
I fully agree, pushback/pressuring would make this unacceptable. But I'm not seeing that in the post, even before correcting for the storyteller's (understandable) bias.
In my mind, the conversation is something like:
"hey can you join this call?"
"not unless you pay me for it"
"that's tricky to set up, but we'll make it up to you when you start"
It's still OK to say no to this, but it kind of feels like you'd start off on the wrong foot. The manager isn't trying to get away with having you do actual work for free -- they are not asking for anything like reports or deliverables. It's just dialing into a few Zoom calls (and "prep", which is extremely ambiguous and could use clarification by OP).
The vacation thing can also be a very real benefit. I don't think a lot of people would take PTO in their first couple of weeks, but your manager can say "thanks for joining the call earlier this month, how about you take this Friday off?"
This is a prime example of the fabled “soft skills”. Humans and our ways are incredibly squishy and ambiguous, so learning to interpret (and dispense) things like “tone” is incredibly valuable.
