Navionics does change things up from time to time. I'm running Navionics US & Canada on my iPhone 5, and can still download maps.

When you zoom out, like the whole US East Coast, you'll see some areas are bright, and some slightly shaded. The bright areas are your stored maps. Zoom into a darker section and hit "Menu" at the bottom of the screen. On the next screen, you see "Menu" up top, and a list. Below the list are two buttons at the very bottom - "Download Map" and "Get Navionics". Select your area and hit the "Download Map" button.

Works fine for me.

John
Cape Dory 36 Tiara