How to convert the pdf to xml file?

Hello Pro!

I am using adobe acrobat pro to convert the pdf to xml file. I click file > save as other > more option > XML, the file converted to xml, however there is no numbers on it only showed the text. I have googled and could not figure out. Can anyone help me how should I do in order to get the xml saved? By the way,  I only picked 10 pages out of the 100 pages as a test, if I convert 100 pages, it's not working at all. Any thoughts or help will be really appreciated!