The SDK for App development is really exciting!
I have successfully built and downloaded an App to my iPad Air 2 (IOS 9.3.1).
This was by hosting it on my a webpage with the appropriate manifest file.
Works well. The app was archived and exported from Xcode "for all IOS devices".
However, when I try to download it onto an iPad 2 (IOS 9.3.1) it fails with
"Unable to Download App" xxx could not be installed at this time. / Done / Retry
Several retries produce the same result.
Watching the App installation on the home screen, it seems to load, then says "Installing"
Then it fails.