Finding Emails for Physiotherapists Not on LinkedIn: Suggestions Needed

Does anyone have ideas on how to find the emails of people who aren’t on LinkedIn without using Clay credits? Context: We have a csv of 15k physiotherapists, including their name, clinic name, and address. Obviously I don’t want to use a Clay waterfall on 15K rows. So far, we’ve tried

So far, we haven’t had promising results. Not looking to pay for services, Just looking for suggestions! Any and all appreciated.