it doesn't work like that machan
unfortunately encrypted files can only be opened with the password the file was encrypted with, so you either have to know the password or guess it.
what password crackers usually do is use a dictionary attack (use a list of common list of words) or brute force it (try every combination of letters and numbers you've specified)
unless the password is very short, this method would take a really really long time(more than a few years

best thing to do would be to download the file again from a reputable source instead of some shady site


hope this helped