Error Trying to download Royals On Mac

I download the client off of Google, and un zip it and it works fine.
Whenever i try to open it this pops up:

Does anyone know how I can resolve this problem.
Appreciate the help

 

First thread in this section: https://royals.ms/forum/threads/mapleroyal-on-el-capitan.39499/

 

Is there any way you can resolve the issue without having to download any programs? Because I remember I used to be able to play on Mac without any issues or other programs such as wineskin or el capitan