In the context of applying to schools, should we use "admission" or admissions"?
Is it an "admission system," or an "admissions system"?
"Configure School Admission" or "Configure School Admissions"
In the context of applying to schools, should we use "admission" or admissions"?
Is it an "admission system," or an "admissions system"?
"Configure School Admission" or "Configure School Admissions"
The system used by a manager at school level manages the admission process for many students. Within schools the admission of a student is typically called an admission, so the system is an admissions management system and "Configure School Admissions" would be correct.
From the point of view of a prospective student they are trying for a single admission, so the system is an admission system. However prospective students will not be authorised to configure the system.
With regard to your question about whether to use "admission system" or "admissions system," here is an Ngram comparison of the frequency of published occurrences of "admission system" (blue line) vs. "admissions system" (red line) vs. "admission systems" (green line) vs. "admissions systems" (yellow line) for the period 1850–2019:

The chart indicates that "admission system[s]" was the earlier form and for a long time was at least slightly more common, but that "admissions system[s]" has been in widespread use for at least the past half-century and appears to have been marginally more common that the form with the singular modifier since the mid-1990s. On this record, there is no reason to suppose that either "admission system[s]" or "admissions system[s]" has an exclusive claim to popular legitimacy.