How to access Android filesystem with Lua?

I want to create mod system for my game. My idea is to put mods folder inside the /sdcard/ directory, so user can easy install mods with file manager.
I modified my game via ApkTool to ask for MANAGE_EXTERNAL_STORAGE permission, and that permission has been successfully granted.

But when I added following code, my game just frozen without creating directory.

My code:

local lfs = require("lfs")

lfs.mkdir("/sdcard/myGame")