In Nanjing, all you need is your ID card to take the exam. You can also take exams in other cities, but traditionally, there are only two exam periods per year, with the last one being in May of this year. The next one is expected to be in November. You can keep an eye on exams in surrounding cities like Changzhou and Yangzhou; however, registration in those cities may require local residency.
To set up a booth, you will need to have a residence permit for Nanjing.