In its "education" chapter, a pictorial ENG-GER dictionary I own translates "admissions" into "Sekretariat" (secretary’s office (of a school or university)), but several online dictionaries give me the meanings "the procedure for admitting students to study at a college, university, or school" and "the students admitted to an institution". Is the translation of my pictorial dictionary correct, maybe as a secondary meaning? I should add that there are instances where the pictorial dictionary features Indian English words, most likely because the book was produced there.
The "Admissions Office" of a school or university is responsible for determining which applicants will be permitted to attend the scool as admitted students.
People who work in schools or universities may well abbreviate "Admissions Office" to "Admissions," spelled with a capital letter. It is a usage that is perfectly acceptable in that context and milieu, but it is not the standard meaning in other contexts. I have forgotten almost every word of German I ever knew, but I greatly doubt that the typical use of "admissions" (outside the context of administering an educational institution) has anywhere close to the meaning of "Sekretariat" in German.