Because the act of linking to a site does not imply ownership or endorsement, you do not need to ask permission to link to a site that is publicly accessible. For example, if you found a site's URL through a search engine, then linking to it shouldn't have legal ramifications. There have been one or two cases in the U.S. that implied that the act of linking without permission is legally actionable, but these have been overturned every time.
Link roundups are selected and organized updates from bloggers that link out to their favorite content during a given period. Roundups are mutually beneficial relationships. It’s really hard to curate content as it involves a lot of work. The bloggers creating these roundups are actively seeking content to link to. You can land links in bunches. Over time, you will gain roundup coverage naturally. After you pitch the blogger who curates the roundup, you should connect on social media. That way, they’ll discover your future updates naturally. I’ve gained some backlinks from link roundups.
Paid search results are those in the top and bottom of the results page, indicated by the small “ad” icon. These are placements that businesses pay for to show up when users search specific keywords. Google Ads can be a very effective way of utilizing ad spend for those who are new or struggling to compete against businesses that rank higher in organic search results. It’s also great for businesses targeting keywords with high revenue potential.