Training gives your body a stimulus to adapt. Pain and soreness are not targets or proof of a good session. You can make progress without either.
Ordinary muscular effort, a new pain and a medical emergency need different responses. Read these boundaries before the course's practical examples. They help you choose an appropriate response; they cannot diagnose a symptom or clear you to exercise.
This is general adult education. If you have not exercised for some time, have a medical condition or are concerned about starting, speak to a GP about suitable activity. Follow any individual advice already given, including for pregnancy, recent birth, an operation or injury.