You have to make your own arrangement to apply for dependent visa(s) for your family member(s).
Also, your dependents are prohibited from taking up employment in Hong Kong unless they have obtained prior permission from the Director of Immigration.
Visit here and submit ID997 to the Hong Kong Immigration Department.
Click here for guidelines to activate your student visa. These instructions will be sent to you together with your student visa/ entry permit. It is important that you do the steps right.
You can apply through HKUST by lodging your application via HKUST Visa System. The University will act as your sponsor.
Please visit here for the application timeline and procedures.
For students from Taiwan, Macao or an overseas country, you may choose to file an application on your own (e.g. through the consulate general of your country). You will need to find a sponsor and make your own arrangement to collect the visa label.