We need five primary school students. Meaning: Kami memerlukan lima orang pelajar sekolah dasar.
'murid' should be acceptable (reported). 'siswa' should be acceptable (reported).
Student (noun) = pelajar, murid, siswa (male), siswi (female)
University student (noun) = mahasiswa (male), mahasiswi (female)
'kami perlu lima pelajar sekolah dasar' is accepted