You will need to find another way to contact that site and request that they stop blocking your access. Cloudflare does not control what site operators block.
While visiting a site protected by Cloudflare, error 1020 “Access denied (Error: 1020)” indicates you’ve violated a Firewall Rule. When this happens, you’ll see the error “Access Denied (Error: 1020)” and your request was blocked by the filter based Firewall rule on the site. If you’re the site owner, you can find the requests that was blocked by the Firewall on the Firewall page under the Events menu. See this CommunityTip for suggestions to avoid this error,