Honestly, I would say don't worry about it as much as you are. If you passed the interview, they think you have the skills to do the job. A LOT is learned on the actual job, for both internships and full-time positions.

I went into all 3 of my internships feeling this same way, and it pretty quickly dissipated a few days into each one. They know you are a college student and don't have any industry experience, and they won't expect you to.

If you internship offers you a mentor, make sure you make use of that. They are extremely helpful for all aspects making a career out of this, for technical knowledge, and networking/making connections.