As Perfect World Entertainment is discontinuing all support for Royal Quest on Arc Games from November 14th, you will need to link up your Arc account to the website to not lose your in-game progress.
1. Go to https://us.royalquest.com and press the Login button
2. Press the “Sign in through Arc Games” button
3. Once you’re logged in, you’ll see “Set an Email and Password” button where the login button was.
4. Type in your email and password and press Enter
5. Download the launcher from the website https://us.royalquest.com/download/
6. Use the email and password you’ve used in the 3rd step.