Prob with extracting

im trying to try out a server and it brings up an error when i try to extract the official L2 C3 client it brings up this error:

C:\Lineage\L2_C3_Installer.zip: The archive is either in unknown format or damaged

It is not because the file is corupted because i have downloaded it on two PC's and both say the same.
Can anyone please tell me how to extract it? I am usinf winrar and have tried winzip9.0 also.
The server i am trying to play is www.lineage13.com sorry for advertising :cry:
Please Please help, thankyou in advance.