Moving Album/photos from Lightroom on my ipad pro (has Ipad OS)to external hard drive?

When you use Lightroom mobile on the iPad, your library and originals are automatically backed up to the cloud. 

Are you wanting to export 999 image copies, fully edited? You can do this by first selecting the images, then tapping the share icon and choose "Save to files" (don't choose "Share"). 

if you want to download all the originals and save them, you'll need to use the Adobe Downloader app on a regular Windows or Mac computer: https://helpx.adobe.com/lightroom-cc/kb/download-lightroom-photos.html