Download the SDL2 development libraries from the SDL homepage. You should find the latest version of the VC development libraries (at the time of writing these are SDL2-devel-2.0.10-VC.zip).
Also, Download the SDL2_image development libraries from the SDL_image homepage. (At the time of writing the latest version is SDL2_image-devel-2.0.5-VC.zip).
Once extracted you should ensure the SDL “include” and “lib” directories are directly in vs/sdl. The tree should look like: