Can't understand the sentences in the readme

[wushu037]

I wrote a program on macos, probably affected by sdl2 so it can not be compiled cross-platform. So I tried to compile the windows exe on windows. when compiling it reported an error

I tried to find the answer in the readme, but I couldn't understand it

The passage:

Install SDL2 http://libsdl.org/download-2.0.php
- Extract the SDL2 folder from the archive using a tool like [7zip](http://7-zip.org/)
- Inside the folder, copy the i686-w64-mingw32 and/or x86_64-w64-mingw32 depending on the architecture you chose into your mingw-w64 folder e.g. C:\Program Files\mingw-w64\x86_64-6.3.0-win32-seh-rt_v5-rev1\mingw64

I downloaded sdl2 and only one dll file was available after decompression

Which folder does Inside the folder refer to? Where do I copy i686-w64-mingw32 and/or x86_64-w64-mingw32 to mingw-w64?