Sorry but what you’re referring to as Windows is actually GNU/NT Kernel…

You dun goofed here. You don’t need to agree to the GPL to use GPL software, so the Next button shouldn’t be greyed out when the checkbox is unchecked. You also only need to show the user the GPL when you give them a copy of the software, so there’s no need to show it during the installation process.

???

Please try to request the source code with that screenshot!

Like, with GIMP, or did you actually change the code somehow?