Mesh is the initial content created. It has colour to it, but sometimes, people want different colours so they'll just re-colour it. If they wish to re-upload it, they will upload the re-colour, rather than the mesh itself. So, if something says 'Mesh not included' or 'Mesh needed', you'll need the mesh for the CC to work.
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Most creators include a link to the mesh they used in their post for the recolor.