Re: Trying to get a hold of AudioTheme iPhone package?
That would be because this is an NVDA add-on, and, thus, only for the PC platform. The developer's e-mail address is listed on the very webpage you make reference to, and contacting him would be the appropriate next step. I very much doubt that there is a version of this for iPhone, but only he can answer that.
As a note for the future, general questions relating to iPhone apps are off topic for the group, though I can see why you asked this one specifically, as someone appears to have stated that there is an iPhone equivalent of the NVDA Add-On. There is no evidence of that at the add-on developer's GitHub page.
Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363
Science has become just another voice in the room; it has lost its platform. Now, you simply declare your own truth.
~ Dr. Paul A. Offit, in New York Times article, How Anti-Vaccine Sentiment Took Hold in the United States, September 23, 2019