You can take the test anywhere, because the Putonghua test is a national examination, and it is most convenient for Zhengzhou school to have a test center. The school organizes students to take the exam 1 ~ 2 times a year, with low fees, around 30 yuan, and no fees for training. I suggest you take the exam at school. You can go to the school test center to buy books, or ask former classmates for them. If you go back to Suzhou for an exam, you will not be a student. You must apply for an account as a social candidate. The cost is at least above 50 yuan, and the training fee is probably around 200 yuan. Textbooks can be purchased from Jiangsu Language Committee Office or Jiangsu Putonghua Training and Testing Center. Guide books for Putonghua are not sold in the society or online, but are purchased at provincial language testing centers run by provincial language committees, and Putonghua testing stations at all levels purchase teaching materials for candidates.

Thank you for taking it as a satisfactory answer.