The Cooling Storage Ring external-target experiment (CEE) spectrometer is used to study the nuclear matter created in heavy-ion collisions at sNN34 = 2.1–2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region. Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions. One of the main functions of the zero-degree calorimeter (ZDC), a subdetector system in the CEE, is to determine the reaction plane in heavy-ion collisions. This step is crucial for measuring the collective flow and other reaction-plane-related analyses. In this paper, we illustrate the procedures for event plane determination using the ZDC. Finally, isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p, d, t, sNN34He, and sNN34He, produced in 2.1 GeV U + U collisions, are presented.