This is to run the PK8ToPK7 Exe https://dotnet.microsoft.com/download/dotnet-core/thank-you/runtime-desktop-3.1.2-windows-x64-installer
This is the exe https://github.com/easyworld/PK8toPK7/releases/download/1.0/PK8toPK7-x64.7z
here's the source code I usually have the exe and source code in a file together https://github.com/easyworld/PK8toPK7/archive/1.0.zip
then just place a pk8 file in the folder with the exe and drag it on top of the exe and a pk7 version of the pk8 file with be in the folder which u can now drag to a gen 7 save file