“So ıf you don’t want to get Failed messages you should install all required plugins first and than you should import demo data.”
That was already done.
Wordpress is at the latest version (4.7.3) and all the Cosmos plugins are installed. (When I said no additional plugins are installed I meant I only have the plugins that came with Cosmos installed.)
“If you are getting “Failed to import Media” you have previously imported some of them or some images not found our server anymore.”
The media directory is empty prior to attempting an import of the demo data. (I suspect the problem is all of the images are no longer on your server).
“These message is not important for the demo content. In any case you need to edit demo content media files as your own.”
I’m sorry, I’m not sure I understand this last statement. I know the images in the demo content will need to be replaced prior to going live, but having them in the demo makes a nice guide to customizing the site. Is it no longer possible to recreate a site like in your demos: https://themeofwp.com/theme/?product=cosmos