Adobe Acrobat Online Tools
Merge multiple PDF files with online Acrobat PDF Tools.
1.Online pdf tools：https://www.adobe.com/tw/acrobat/online.html。
Sign in or create a free account. "Start free trial" means downloading the 7-day free trial version of the software.
2.Select "Combine Files".
3.Upload PDF files of each chapter
4.You can adjust the PDF order in the editing area, select the pages and enter the file name to save, then click [Combine] in the upper right corner.
5.The completed file will appear at the bottom of the page. Click the [...] icon on the right side and click [Download] to download the merged file.