I assume you mean Game of Thrones Ascent? I can get to its sign-up page alright, where it asks to register which I don't feel like, so haven't tried beyond that.
You may be blocking something at your end, see here & onwards from there for suggestions on how to fix this.
... ps, It's always possible of course the game's server(s) is/are going through some hiccups. That could well result in my getting to the start-up page, but your not being able to proceed beyond that.
There'd be nothing for it but to wait for a while and hope they go back up, or report back here if it persists say after a few days.
