How do i get my travel drive to work on my schools computer and at home?

I bought a travel drive a couple days ago. I used it on my computer first. I needed to type a couple essay on it. When i brought it to school it wouldn’t let me open it. It kept saying that i have to be a privileged user. That i can’t be a guest which is what i am when i use my schools computer. How can i fix this problem so that i can use my travel drive at school as a guest and at home. Please help.