1. Figure out what compiler you are using? You stated GCC
1b. Figure out if the GCC is 64 bit or 32 bit?
I choose to use an 64 bit MinGW GCC.
2. Set the value of the SDL2 Global Variable
I used the base value of "C:\Users\stahta01\devel\libraries\SDL2-2.0.12\x86_64-w64-mingw32"
without the double quotes. Please choose a path without spaces and using only ASCII characters.
3. Run the wizard; note, I have you set the Global Variable first because it avoids a Wizard warning/error.
If you have questions about a step ask them!
Edit2: Before you try to use someone directions; it is a good idea just to get the wizard code to work.
This way you know the Library and the Compiler are working okay.
Most people use "Lazy Foo"; but, I did not like the license.
I tried to use
https://www.willusher.io/pages/sdl2/ but decided to stop when something else happened in my life.
Tim S.