As you might have heard of Adobe has discontinued the Flash Player and it's not longer supported by them, Some players might have an issue of launching the game.
However, You can download and install this handy flash tool kit to avoid having this issue.
It's a common error for all new Conquer Online clients, So make sure to follow these easy steps listed below:
1. Close the game.
2. Download the UzN-FlashPlayer.rar.
3. Install the UzN-FlashPlayer and reboot your computer.