I'm using Blender 3.6.something.   1. Install Havok Content Tools (google HavokPcXsContentTools_X64_2010-2-0_20101115, it's fairly easy to to find it) & grab the archive i've attached:  Blender_to_skyrim_in_39_easy_steps.7z   2. In Blender, Edit -> Preferences -> Add-Ons -> Install button, install blender_niftools_addon, and tick the box so it's active.   3. If you've installed Havok Content tools in a non-default folder, edit the _convertSEtoLEto