I got a Tinder account (I know) but I got matched with this girl. I want to message her but she goes to my college and I'm always running into her. If I start a conversation and she dislikes me it'll be so awkward. What should I do? (by the way I'm a girl).

Easy. Strike up a normal conversation, like "Hi! I'm ___." And then slowly get to know each other. If you are into females and she is a female, casually and discreetly ask her if she's into females as well. And if so...there ya are. Start slow. As friends. And build up a relationship from there.