You must have financial need to be offered a Work-Study award. You must have met all the requirements for receiving financial aid that is expected of all financial aid recipients. Generally, your file must be complete and you must be in good standing with the College.
However, just having financial need is not always enough. For example, you may have all your "financial need" being met by scholarships.
If your financial need is being met by a combination of scholarships and/or grants and subsidized loans, and no Work-Study is listed, you might be able to convert your subsidized loans to Work-Study.