So I downloaded the entire file at once (2.1 GB), but all I have in my download folder is a download file and two BIN files. I can't find a setup .exe anywhere. Help?

rename gogDownload extension to.exe. Sometimes downloader doesn't do this automatically although it should.

I changed it, and it worked. But it says the files are corrupted. I did some digging around and people say to manually download each packet rather than all at once, but those don't seem to zip... they just download, I open, and it also says corrupted. Le sigh.

You really want to avoid the downloader if at all possible. It does not behave with a great deal of antivirus and antispyware software. For some reason Adobe just doesn't get along with certain programs.

I would try, if you must use the downloader, deactivating your AV while you redownload everything individually. Also, before you do that, delete all traces of the game currently on your system. At this point, you may have to rename the main file again, but I'm willing to bet it's not corrupted.

The alternative method is to download each bit through your browser, but again you may need to disable your AV software to get the game to a non-corrupted state.

Hope this helps, and welcome to GOG, Grimgak :)

Happened the same thing to me, and I did rename the file and got the "corrupt file warning".
I undid the name change, downloaded only the 2MB .exe (First link I think) , and instaled without a problem.
/Phew

Kudos to Thiev.