Cloudflare is compatible with websites using SSL, however, you must use one of the paid tiers of Cloudflare to enable SSL. To upgrade a free Cloudflare account that was created in your Impreza cPanel, please contact our support team for assistance.
Once you have upgraded to a paid Cloudflare account, the process to enable protection for SSL varies. You should start by consulting this Cloudflare article, “How do I add SSL to my site?“