The first sentence is more appropriate:
"I am studying hard in order to pass an exam and receive a license as a psychiatrist."
In English, the terms "license" and "certificate" have distinct meanings, especially in professional contexts:
- A license is an official document issued by a governing authority (like a medical board) that gives you legal permission to practice a profession (e.g., psychiatry, law, etc.). Without a license, you cannot legally work as a psychiatrist.
- A certificate is often a document that proves you completed a course or training. It doesn’t necessarily grant you the legal right to practice in a regulated profession.
Since psychiatry is a regulated profession, you need a license to legally work as a psychiatrist. That’s why the first sentence is correct!