For some books, you may not need software, as Google Books allows for a direct download in PDF format if they are in "Full View".
If you are using an older version of the tool via a ZIP file, the process generally involves these steps: melon google books downloader zip
A Convenient Tool for Google Books Downloading For some books, you may not need software,
These tools are designed to facilitate offline access to materials found on Google Books by automating the process of saving pages. Offline Access For some books
You scroll through the book pages manually to load them into the browser's cache.