South African living in USA going to China for business for up to three weeks. What do I need to do?

Currently trying to find out if there is anything special that I need to do to visit PRC with a South African passport. I will be traveling from Los Angeles, back to Los Angeles, and I just wanted to know what the steps are for doing this.

So far, I have seen that I may possibly need a letter of invitation from a resident there, and to fill out an application form. But in other locations, I am seeing that it gives you 30 days of free time that does not require one. Just a little lost here on what exactly I need to do and the Chinese consulate is not answering the phone.