Hi @spaulrob,
Thanks for the inquiry and posting to the Roku Community!
The Roku app for iOS is compatible with Apple devices running iOS version 11.0 or higher. Visit the App Store on your Apple device (iPhone, iPad, iPod Touch), or visit the online App Store to download the Roku mobile app for iOS.
For full information on this, you can take a look at this link: How do I install the Roku® mobile app?
Let me know if you have any other questions, and have a good day!
Thanks,
Mary
Mary F.
Roku Community Moderator