Check these links
- Adobe Lightroom for mobile FAQ
- Get started with Lightroom on mobile | Adobe Photoshop Lightroom CC tutorials
Read all of them carefully and follow the instructions.
Your desktop version is fine - the CC version - and enable sync in your catalogue. If you get an error message, please quote the exact text.
Just go the the App Store and search for Lightroom for iPad.
Is Lr on iPad not free for registered CC users?
It's free for anybody ...