Anything other than that? I am guessing it says something else, I would disable any antivirus programs and browser security settings and download the setup again.
Can you upload a screen shot of the error, just to make sure I know I'm dealing with the correct one? Also, what kind of operating system are you running?
Don't listen to all that bull wonky about disabling your anti-virus program. It won't do shit for you. I assume you're on a windows 8 machine because I always got that error. To fix it all you have to do is right click your MapleRoyals.exe and select properties ---> compatibility ----> Enable windows 98 compatibility and bam you're issues are long gone.