I have the same problem. I see the link points to https://help.thumbtack.com/profile/pro_referrals but it immediatly redirects to the thumbtack.com homepage. If i manually enter this URL it lands on an error page with "URL no longer exists".
@OxleyPC a quick follow up on this. The referral program is currently only available to pros that have had more than one contact in the past 60 days. A pro only needs to qualify once, and then the link to their referral page will always be available to them.