Here is the link: https://expt.pcibex.net/ibexexps/CBill/NDC_Child/experiment.html
I have been playing around with it a bit, and I think it is something to do with the audio files, as when I remove audio files from an item, it loads immediately.
I have tried .mp3 and .wav audio file formats and both seem to have the same issue. Could a different format work better? We will be running this experiment in daycares using the same 1 or 2 iPads, so it would be fine to have the files in a format that only works on iPads or certain browsers