Just FYI RetroAchievements has "nothing" to do with LaunchBox, launchbox only polls RetroAchievements for your achievements and displays them. Its really between RetroAchievements and RetroArch that is important.
First go to RetroAchievements.org and create account.
Now you can add Username/PWD via the GUI, but I had a long complex password and I couldn't paste into the GUI so I edited retroarch.cfg manually and added the following:
- The hardcore mode prevents you from using emulation features like slow motion, cheats and savestates. BUT gives you double points.
- Verbose = On Screen Achievements display.
In Launchbox, go to Tools >> Options >> Retro Achievements. You need to have your browser open and logged in to get the API Key by clicking the hyperlink then paste it back into application. Thats it.