I do not know of any poster that uses passwords that does not follow the standard. Once you learn how to deal with them, it will be the same technique no matter the poster. The only thing that will change between posters is the password itself and the poster always uses the same one. The unprotected text file contains the password. The text file will unzip without the password.
All passwords are all capitol letters.
Use any unzip technique described above then read the text file. To tell pkunzip to use a password you must use the -s switch as follows. Open the zip, under options, password, enter the password. Open the zip, on the extract screen enter the password. Once you learn the password for a poster, you will not need to read that text file again.