goto C:\Users\%username%\AppData\Local\Larian Studios\Launcher

is there a Cache folder?
the 3 HF files from gog are;
<File size="116268017"
hash="deaab84407cf4882db91d76517992d1d">Data/Patch9_HF1.pak</File>

<File size="240195357"
hash="d1b864b81f1c2b9b0484ecbe0a4ffd77">Data/Patch9_HF2.pak</File>

<File size="87766954"
hash="a1798595805c0298ca48d94d897982cd">Data/Patch9_HF3.pak</File>

Luke Skywalker: I don't, I don't believe it.
Yoda: That is why you failed.