Hi Javier,
It would be best to approach her in person rather than by text.
Being that she doesn’t know you, approaching her in person makes you come off as confident. This is a quality that will instantly elicit a good first impression on her.
The next time that you see her, approach her and start a conversation.
Being that you are both in university, you both already have something in common. You could start with asking her about what she is studying.
Show interest in what she tells you, try to relate to it in a relevant way and ask follow-up questions.
If she likes you, she will want to keep the conversation going and may start asking you questions about yourself as well.