Your question is Rate Limiter Design. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Design or implement a Rate Limiter.
Asked in the Phone Screen stage. The author described this as a practical phone-screen question and not difficult. Explain your design or implementation clearly, including the algorithm and important edge cases.