There’s no place where we are asking you to diagram the system that you’re working on. We ask you to diagram a system you understand well. Are you using messages queues, container orchestration, network components, cloud infrastructure, Java/rust/go/Python/etc.? Tell me about one of those components and how they connect together in theory vs the specifics of your system. Everyone who works in technology works with, mostly, complicated interconnected systems. The point of this exercise isn’t to design a system or tell me about a system that you’ve designed as much as it is about helping the team to understand the breadth and depth of your technology knowledge. Good engineers typically find creative ways help us understand their knowledge without disclosing NDA material.
I feel like I'm either losing my mind or people are being deliberately obtuse now.
He's not saying they ask you to give a full overview of the way Apple architects their systems, he's saying they ask you to explain how a basic Kubernetes deployment might look, or how you might go about setting up some kind of backup system, or literally any of a million different technical things that you might have knowledge of and interest in.
How could things like this possibly be under NDA? If you weren't able to use any of this knowledge, you would be completely crippled in your work.