How does RSI pair you up with professors/researchers?

I’m working on my RSI essays, and one of the questions is about why I want to attend. I’d like to talk about a lab (and professor) at MIT that is doing research that is perfectly aligned with what I want to do, but I’m not sure how they assign students to different professors/researchers. I suppose I should just write about what I want to do, but I also don’t want them to dismiss my application because lab X or Professor Y isn’t participating. Not sure if that question makes sense? Any RSI alumni able to chime in on how it worked for them?

Just mention the lab/prof and say you are intrigued by their work.