Is Chengdu Huaxing College a correspondence course?

Yes

The diploma from the Vocational and Technical College is a training certificate, not an academic certificate. It only proves what training you have received and has a certain skill level. Participating in various recruitments cannot prove you. However, some professional colleges and some universities jointly offer some adult correspondence education, and you can also obtain a college or undergraduate degree in adult education, which is a nationally recognized academic qualification.