I figured it out!
Turns out, the zip contained .unh files, which is not supported. I've got some new files and it's up and running. As of n64, I had to unzip each file to get them to run.
Bonus question: is there something I can do to get n64 to run more smooth (rpi 3 B+)?
Again, thanks for taking your time. And for future googlers, hope this help you out.