I would like to know if one were to commit Zina with 3 women. Does he have to take 300 flogs or 100? And does it purify one from the sin and wrath of Allah

If the person has committed Zina with 3 women differently, he will be punished for each time of his sin that means he will take 300 flogs totally, 100 flogs for each zina. A person just gets rid of the punishment of hellfire if he takes punishment in this world but such a person should always repent of this big sin to seek the contentment of Allah (SWT).