How do I dress professionally when I'm scared I look out of place?

That worry about looking out of place is heavier than the clothes themselves. It sits with you all day, stealing attention you would rather give to the work. First, be kind to yourself: no one is born knowing what professional looks like. It is learned, usually by quietly watching others, and you can learn it too. Keep it simple to start. A few clean, well-fitting basics in plain colors will carry you through almost any workplace. You do not need a large wardrobe or expensive things. Fit and neatness matter far more than labels. When your clothes fit and are cared for, you already look like you belong. And remember that most people are thinking about themselves, not studying you. The fear of standing out is usually larger than the reality. Pick an outfit you feel steady in, wear it, and let the worry quiet down. Confidence comes not from perfect clothes but from deciding you have done enough and turning your mind back to your work.