I do not think you are able to download the wrong version by simply clicking that large "Download / Install" button on our homepage.
Not even you.
It will ask you what you want to do with the illarion_client.jnlp, and you want to open it.
Of course, you need Java installed for a Java-Client to play.
But before you make me write essays about what could go wrong with end-users and software,
why don't you simply tell us *what went wrong* !?
you didn't, our noble gms and devs use to write their answers sarkastic, just write what went wrong and i am sure they offer you a solution.. maybe in a sarkastic way, but their solutions are solving that kinda problems, and complete their mission.
So don't take it personaly
probably not if you keep in mind i only asked it once, i dont know how many other people asked the same thing, i wasnt able to do a forum search or write what went wrong, when i didnt know what was wrong.
Just don't be so horribly annoying vague when you ask something.
Providing information about your problem is the first, and most nessessary, step in finding a solution.