POPCORN is integrated with many WordPress plugins such as Ultimate Member, Paid Memberships Pro, bbPress etc. You can find the full compatible plugins in this category.
You don’t need to install all plugins in the list you may need BuddyPress without bbPress or you just want a pay per view site using Paid Memberships Pro so you can ignore some plugins if you are not using them except Advanced Custom Fields which is required on our themes.
If you need a child theme or want to import demo please navigate to the WordPress Dashboard -> POPCORN -> Setup Tab check your system info and start the wizard.