My site is not Procted by Cloudflare

Hi Cloudflare Community
I am facing an issue that is, I am using Ionos Hosting and use the external domain to link it. Ionos not providing SSL for free. So I tried to link my site with Cloudflare for an extra layer of security. My site status is showing Activated by my site is not live showing 503 Error[.] Can you please share me the solution, I am very thankful for this act.
Thanks Cloudflare