I think that section is for those who sell at the marketplace. Since they are not allowed to sell stuff like “Coca cola megapack” or “Fortnite character pack” or whatever 
And without being a legal expert, if you legally acquire assets from the marketplace (free or paid) then they are licensed to you. Which allows you to use them in the ways stated in the license (which more or less is that you can use the assets in a packaged game or rendered video, including tutorials)