Maybe I am slow, because I have had to read these posts multiple times to ensure what I was reading is correct. One of you wants to open a .zip file that is password protected. That means it is encrypted. Encryption and compression are two separate things, though in this case they are both applied to this file.
WinZip has a shareware version. So, that is not a real problem - I don't know why it would be to begin with.
Stuffit can open .zip files, so that is not an issue either.
What you need, is to be able to decrypt the file. The programs you are attempting to open it with have nothing to do with your lack of a password. They are only doing what they are supposed to do.
Do a Google search for '.zip password recovery' without the quotes. There a multitude of programs to complete the task.