You’d have to get it on your own for the summer between sophomore and junior years. The summer recruitment is for rising seniors.
However, you can avail yourself of services in the Ross career office. Make an appointment to get help with your resume and suggestions about how to go about getting an internship on your own. My daughter did that and found it very helpful.
If you want an internship in banking, you have to start in September/October. But again, it would have to be through your own connections or just applying on your own. If you are looking for something in other fields, like marketing, human resources, corporate communications, etc., you don’t need to start looking until January. Even that is kind of early.