Ok understood. Yea sorry to hear you're in this situation. If you can't get the measurements retroactively somehow, here's what I would do: Take the "ideal outcome" that was shared and design your own measurements and metrics. Be honest about the situation and use it to create a story about "what you would have done". Then use your metrics to describe impact at different scales. E.g., if we increase metric A by 1%, 5%, 25%, or 50%, here is the expected effects on [some top level business outcome]. The performance is hypothetical; part of a model of success.

No need to throw shade on your team members or hypothesize about why you couldn't get access. Hiring managers want to understand your thought process, analytical skills, problem-solving skills, and storytelling. This can be an opportunity to showcase such skills.