I never worked on this stuff so it's not for me. Sorry.
I just noticed that while using this key:
The zip produced, has some data at the end of the file, and the rest is all 00, that means because of modified ZIP structure. according to others who dealt with this format in different games.
So basically the decryption happens but it cant read data inside .pak due to new ZIP structure.
If you are curious about it and would like to look at it please do.
Because if decryption works means you can read and analyze the archive, correct?
I have included an old sample that works and the new one that does decrypt
but different structure, for you to analyze the differences between them, and maybe actual extraction can happen.Sample