There's a thread about Where to (legally) acquire content to play on RetroPie. Note that the thread starter can't keep up with updating the list in the opening post with the stream of suggestions from others there. So, after reading the list, you should also skim the thread backwards from the end to see the most recent suggestions.
We don't support 3rd party images, especially the ones loaded with ROMs - as are the ones that you're trying to choose from. Use the image from retropie.org.uk/download and follow the installation instructions from the Docs.
If you're hard pressed on time, I recommend you get your brother friend a ready made console, like one of the mini consoles released by Sega/Sony/Nintendo, which come already installed and with the games included.
I can strongly recommend the Crush Pinball series, especially Alien Crush and Devil's Crush (Devil Crash in Japan) for the PC Engine / Turbografx-16. They're often mentioned as maybe the best pinball console games ever made.
Pinball Dreams and Pinball Fantasies are also worth a look. The Amiga versions may be the best because of the music, but the console versions are also quite good as far as I tested them.
I didn't notice any problems running any of them on my non-overclocked Pi 3b non-plus except for the Amiga versions, because I my Pi is only used for arcade and console emulation.