The web-app will work on any mobile device in any area with internet coverage. Before people travel away from this zone they are encouraged to download the guide to embed the map content onto their phone.
A major advantage of using the PDF format to embed content onto the phone is that it can download a very large body of content and mapping material without exceeding the 50MB download limit beyond which wi-fi is required.
This is because it is content only data that is being delivered. The coding to interpret and present this content is already in place on the phone's PDF reader app.
A typical file size is around 15MB resulting in smooth and simple downloads for most users in most settings.