Finding the "ROMs" (technically called "Game Dumps" in this scene) requires knowing where to look. Because these are files from actual arcade hardware, they aren't hosted on the official TeknoParrot website.
For a true arcade cabinet experience, many users integrate TeknoParrot into Import Process : You can import games by dragging the game's profile (found in the UserProfiles folder of your TeknoParrot directory) into LaunchBox. Command Line teknoparrot roms download new