You can you any plugins you want. Some demos have forms that are built through the “MailChimp” plugin, so in case you do not want to use it, just rebuild the form per the plugin that you want to use.
As for the “Save SVG”, I suggest using it always, as it prevents SVG/XML threats from potentially affecting the site.
Also allows you to view downloaded SVG files in the media library in all sizes and etc.
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