How do I Export with file's sub folder structure?

Hi,

is it possible to maintain sub folder structure of files after exporting.

No, it's not possible. You can restore the folder structure in the exported game, but you'll have to add folder names to file paths in your events. For example, if you had AJAX Request MyArray.json action, you'll have to change it to AJAX Request "FolderName/MyArray.json"

Of course, if you do this, the game will no longer work in preview.