Hi there -- what exactly do you need? I use the map pack on Mac (there is a separate download for the Mac version, it seems). Do you actually have the map pack? If not, I'm sure I can get it to you somehow.
As to *where* to install it, I don't have any experience of Linux, but it might be similar to Mac, given their Unix-like ancestry. The path on my Mac is: /Users/username/Library/Application Support/Steam/steamapps/common/Sid Meier's Civilization V/Civilization V.app/Contents/Assets/Assets/Maps/
Apologies in advance if that is no help.