Generally, a debit card is used to deposit money first. Cannot overdraw. Credit cards are debit cards, so you don't need to save money. You can overdraw and withdraw cash within the approved limit, but you must repay it within the specified time, otherwise your credit record will be affected.
If you want to apply for a credit card, you can apply at the counter of ICBC, and they will specifically ask if your conditions are suitable for processing. For debit cards, you can fill in the application form at the counter and get the card immediately.