Just follow instruction after buy of plugin. Usually plugin works for Mautic 4 and Mautic3 as well and download link for Mautic 2 is included in plugin zip package.
If plugin has different Mautic 4 and Mautic 3 version, by default you download Mautic 4 version. Download link for f Mautic 3 and Mautic 2 you are able to find in the zip package.
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