Where to store non engine data files and how to pack them to build?

Where should I store files not recognized by Unreal Engine but used by my game to store some map and configuration data?
FPaths::Game*Dirs provide me with links to some folders, but shou;d I use them?
For example where I should store custom maps created by user? In save game data dir?

And how to deploy them? If i have some prebuild custom maps, should I put them to build by hand or there is some UE support for this?