Expect the interview to last at least an hour. There are second interviews before you're given an offer. The second interview will come with a "homework" assignment, usually. You'll be given an hour or so to come up with some sort of organizing plan/political analysis/etc. Depends on who your boss will be, but interview process can be super laid back and informal or a bit more stuffy.

I interviewed with the organizing director who said they would get back to me. I wrote them a couple of times to ask if they'd filled the position. They responded they needed to do a second interview to which I agreed. This process was now in its 60th day. After the second panel interview that appeared to go well it was an additional 90 days before I finally withdrew my application. They said there were so many qualified people for the role it was just too hard to make a decision. I wouldn't work anywhere that has this much issue with communication and transparency. Whether intentional or not, massive red flag and i'm glad i avoided it. They still haven't filled the position well over a year after I withdrew my application.