UTM Tracking - You might choose to use UTM tracking, which can be setup in the settings of an account, campaign, or ad group.
Some potential reasons are you are in a competitive industry, you have other key phrases that have proven to convert, there's low search volume, and where you are searching (Google) from.
It is likely that LinkedIn campaigns to warm leads (aka remarketing) could be a good fit, but LinkedIn campaigns to cold leads is only a good fit for a few narrow industries.
You will see consistent correlation.
DSA Campaigns are used as learning experiments - You may choose to build dynamic search ad campaigns because they help you learn what ad copy & keywords to use in the other campaigns, in case you missed any important and effective words.