S4S only supports versions of Blender that run on all versions of Windows that TS4 runs on. That ensures that anyone who can run TS4 can run an S4S-compatible version of Blender while keeping the number of separate Blender versions that must be supported to a manageable number. It is possible to work in a newer version of Blender and use an older version as bridge to get meshes into S4S.
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