Learners being prompted for atticulate download

Hello
Using storyline we have recently published to web a package - good so far!

A learner then has tested from home on her ipad, viewed a couple of screens in the package and then was prompted to install an Articulate APP to continue, which she as not sure she paid for or not? Is this correct, that this APP has to be installed or is it something to do with the publishing settings that I have set - below -

Checked - Include html output
Checked - Use Artilcuate Mobile player on IPAD
Checked - Allow downloading for offline viewing

Thanks Hannah