You’re guessing correct now (except that it’s not G-code, it sends waveforms that direct the motors & power supply).
That means if the job doesn’t fit in the memory then it won’t work at all. But they’re working on a feature that will allow it to fill the machine’s buffer, execute and then refill it as it goes through what’s been loaded. That will provide the ability to do longer more complex jobs and they’ll be implementing “Pause & Restart” support so you can stop & restart a job or you could restart after a power or network fail.