Im getting the same message as you when I'm downloading the client (I'm using a mac). Ive tried both Safari and Chrome. However, if i click the link enough times on chrome, it sometimes does load properly (Like, after 40 attempts lol).
I also have problems connecting, even when i have downloaded the game. But i dunno if thats a mac problem in general, or just my computer. Some days it loads fine, some days it doesn't connect to the server at all. Ive only started playing since the Hoenn release, so i don't know if its just a recent thing.