There is no correlation between university application requirements and Diploma courses. Universities do not accept Diplomas for admissions or applications.
The minimum requirement for university applications is having a Bachelor’s Degree Matric Pass. Since there are many university applicants, this still does not ensure acceptance. The higher your marks are, the more likely you are to get accepted. There are also many other entry requirements that are specific to each university course, so you will need to make sure you meet these as well.
Other requirements could include having completed specific subject sets, extra documentation, practical experience, or high marks in stated subjects.