Doctoral candidacy is not the same as admission to or enrollment in a doctoral program; it is a specific stage of doctoral program progress. https://catalog.unl.edu/graduate-professional/graduate/degrees/doctoral/#candidacy
Apply for Candidacy: http://www.unl.edu/gradstudies/current/Doctoral-Candidacy.pdf
Once a student becomes a doctoral candidate, the student is required to enroll continuously until the program is completed.
Request for Certification of Full Time Status: http://research.unl.edu/gradstudies/fulltime/.