Hi,
It's always recommended to use the latest version of Ansys. In this case 2022 R2 (Download Ansys Student | Workbench-based Simulation Tools).
Only the Student Version of Ansys is available for free. The Student Version has some problem size limits, mentioned below:
Problem size limits on Student Version:
      Structural Physics: 128K nodes/elements
      Fluid physics: 512K cells/nodes
      Electromagnetics: N/A
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