Hey there david hopkins1,
Thanks for reaching out to Apple Support Communities. I understand you have a large amount of PDF and other documents you want to read on your iPad and sync via iCloud. I’ll be happy to help with this.
With iCloud for Windows, you could add your PDF and other documents to iCloud using iCloud Drive. Take a look at the following article for more info on this.
Work with files and folders in iCloud for Windows
Once you have your files there, you can use an app like Books to view your PDF files:
Save and mark up PDFs on your iPhone, iPad, or iPod touch with the Books app
If you don’t have Windows for iCloud set up already, this link can help you do that:
Download iCloud for Windows
Cheers.