Ethical dilemma! Need advice

I recently was given a flash drive from a classmate and told that on it were study guides and notes for our next semester classes. The classmate that gave it to me is someone I’ve had clinical with, not close friends but someone that I believe I could trust. They told me that my group was the last group in class to get the flash drive which made me pause and ask if there was anything we shouldn’t have on the flash drive. The reason this comment left me with concern is that our class has a special facebook group just for us that we share files with all the time, so I didn’t understand why the information on the flash drive wouldn’t have just been shared that way. When I asked them if there was anything on the flash drive that we shouldn’t have , they told me no , that there were just study guides and notes. I just went on the flash drive and there are notes and study guides but there is also a couple files labeled test bank. I personally don’t agree with test banks and would never use them but I wouldn’t go out of my way to to tell on someone for using it because in my opinion it will catch up to them eventually. My issue is that my school is against test banks, they even make us sign a document that says we will not use test banks. I don’t want to get people in trouble but now I am worried that if somehow it gets out that our class is passing around test banks that my name will get thrown in there because they gave me the flash drive,even though I don’t plan on using it. So now I am torn between confronting my classmate and giving them back the flashdrive because I don’t want my name part of any of this or going to one of my professors and giving them the flash drive. Or am I making a big deal out of nothing and I should throw it away and not worry about what the rest of my class is going to do with the information. Any advice on this dilemma would be much appreciated.