Of course you can bypass the password check by cracking WinRAR. But this will not help you, since the data is encrypted. Without the correct password (or password-hash) you will never be able to decrypt the data in a way it could be decompressed. You should better read a bit about the basics of cryptography, if you don't understand how this works.

And when I read the "hints" the author gave you, I was 100% sure that it's a fake. WinRAR doesn't have anything to do with PGP SFX and nothing can be done by modifying the file headers.