Before officially reporting for duty, the company provides an opportunity to sit in as an intern. If interested, you can first experience the workplace atmosphere and job content. It is intended to help job seekers assess whether they want to join, which is a considerate approach and avoids making hasty hiring decisions.
So far, I feel it is okay. At most, everyone may be quite busy because there are many customer orders, so you do need to work proactively and diligently.