Q: How do I sync my iTunes library on to my new iPad after I have already backed it up through iCloud ?'l

As you can see here, iCloud does not back up your iTunes library:

iCloud: iCloud storage and backup overview

You linked an article above about transferring content from an iPad to a new device.  The only content that can be transferred that way is purchased content (from the iTunes Store).

If you have a new computer and want to get your iTunes library onto it, it must come from your old computer (if it still functions) or your old computer's backup.

The exception would be if you purchased iTunes Match, in which case your iTunes music would in fact be stored in the cloud.