I want to apply to RSI to pursue stem research relating with autism, what should I do
I’m not really sure what you mean by “what should I do.”
If you’re currently a junior, you can apply! RSI asks you to write about the areas of research that interest you, you could write about that.
However, keep in mind that RSI can not always match you to mentors doing your exact area of research. They try very hard, and pretty much everyone has an incredible experience with mentorship. However, there is no guarantee you will get to work on the specific problem you applied for, and no way to know ahead of time if you will.
Wait, how specific do you have to be for the field of interest? I put:
- Biology (Subfield: Molecular Biology)
- Chemistry (Subfield: Bioinorganic Chemistry)
Looks good 
You can just talk about it in the personal statement