The 'Pack' feature supplements your regular downloads. There is no need to access the 'packed' items directly. The items downloaded using 'Pack' are for your planned route of flight and are accessible as you use the features within ForeFlight Mobile. For instance, if you want to look up airport information for an airport along your planned route, you can view the downloaded 'Pack' information for the airport in the Airports page. If you need to view a map on your planned route, you can do so on the Maps page.
You will be able to note the downloaded Pack items under MORE > DOWNLOADS. On this page, you will see "Packed and Unselected Regions" listed in each section for those items you have packed that are outside of your regular downloads.
Please see our blog post about Managing your Downloads and Pack.