The resume and application materials have been submitted and reviewed. You have qualified for the position and have been scheduled for an interview. You have a real shot at getting this position. You should be. That's perfectly normal as well.
Most people get anxious as they anticipate an upcoming interview.
Qualified or not, you begin to question your ability to sell yourself and your skills. You create worst-case scenarios and are sure you'll say the wrong thing. Again, all of that is to be expected. The main difference between those who do well, and those who don't, lies in your willingness to practice and your ability to provide examples supporting the knowledge, skills, and abilities you'll bring to the job. So be nervous, but also be prepared.