Is it possible to download my music (NOT APPLE) from Dropbox to my new iPad Pro, and if so, how?

You can use the DropBox App to download the music from DropBox servers onto the iPad but it will remain in the DropBox App, and should be able to be played in there.

You can also alternatively use a 3rd party App such as CloudBeats music player on the App Store

to download your music from DropBox, and play it on the iPad.

You cannot download from Dropbox into the default Apple Music App however.

Sure. Any questions you may have are very welcome.