The wordpress file editor only supports php and css files not less files.
So if you want to use less code, use the customcss box under custom code in the settings, or use the style.less file in your child theme or customize plugin and edit it over FTP.
Is it correct that you need to upload the pagelines style.less.zip file to use Less in combination with the customize plugin? if I want to use less code (without using a childtheme) this tabel says the framework allready supports the CSS/ LESS Editor. So why to upload this file at all?
If you just want to use css, the again either use the custom code box, or style.css in child theme or customize plugin, but this time you can use the wordpress theme/plugin editor ( if you want to, its not supported by us).
Ok not supported, clear, but does this mean that when Pagelines Framework runs an update the custom css code is lost as stated in the following text??
You’re unable to customize the Framework further by editing core files such as style.css, as this would require editing the core files (something we do not recommend or support), any edits made to these files will be removed upon updating PageLines Framework, when an update is available.
I assume we're talking about the style.css file displayed in the wordpress appearence-> editor?