Recovering pre-October 2024 OneNote files on iPhone 16 and iMac

Please tell me in clear non-tech way that a novice IT guy could understand. I need a simple step-by-step description of how to recover OneNote files history prior to October 2024.

[Re-Titled by Moderator]

Original Title: Clearly describe how I recover my OneNote files from before October 2024 when I transferred all data to my new iPhone 16 the OneNote files did not transfer to both my iMac or my new iPhone. How do I recover this critical information?