Go to your Notion and find the database you want to analyze. If your database is displayed as an inline view on a page, make sure to open it as a full page (refer to the screen below). Otherwise, you cannot download it.
Go to the three dots "..." located in the top right corner and click 'Export' to download it in CSV format.
Go to the downloaded file on your computer and unzip it. Now, you will see your data in CSV format.