Leverage LinkedIn Marketing platform to fill up your pipeline. Deliver an irresistible downloadable empathetic to their needs/pain points and deliver it via an Inmail and sponsored post campaign that informs but doesn't sell. Target by industry, title, geographic, company size overlays. Capture pixels from Google, Facebook, Twitter on your download landing page to facilitate retargeting on the clicks.

Ignore LinkedIn's suggested bids and turn off auto bidding, start at the minimum and lift it slowly. Check your demographic chart to be sure that job titles are CMO/Marketing directors.

Good luck!