Nonprofit salaries are generally not as high as other sectors. There are still good reasons why lots of people would want to work for a nonprofit, particularly one as prestigious as MoMA. And that is more than livable, even in NYC.
No, it's not.
I promise you, you're not going to be homeless at 150k.
What kind of legal agreement are they asking you to sign off before the job application?
Sounds like CloudKitchens. Cloud Kitchens engineering managers cold emailed and then told you to sign an invention assignment agreement just to do the first call with the engineering manager.