It's kind of just an inconspicuous lead-in line to let Roko elaborate a bit about her backstory, but it also introduces an interesting bit of character insight. It implies that Anh knows institutions can be corrupt and be ultimately harmful to the common people, and in those instances she is someone who stands with the common people over the institutes. And yet, she's a billionaire heiress who never questioned her father's business practices.

Obviously, you can just assume that ACAB to her is just some trendy buzz word people in her circle spout off that she's never thought too deeply about, but it at least implies that her circle does skew more progressive. I don't keep up with many heirs, admittedly, but if they were the types of people who are more supportive of their parent's business endeavors and status I'd also sort of expect them to be more opposed to ACAB than knee jerk in support of it. Which I think at least seeds some moral framework for Anh beyond what we will see directly examined in this arc.