Getlost Maps

[Tomm0]

What app is needed on my iPhone for these to work?

Any one of several. Oziexplorer or Avenza are what most people use because both work fine and will run all of the maps at once without paying anything, and that's the core philosophy - that you should be able to use them for free.

They're in multiple formats which should cover most software, or you can convert them if you want to another format if you have a different app.