SSL issues -'not secure'

I’m getting ‘not secure’ instead of the padlock on my domain:

http://rhythmnutrition.com/

I’ve clicked the SSL button here:

For your information, I connected my GoDaddy domain via the webflow API yesterday, all seems to work fine. I did publish the to the domain BEFORE I clicked the SSL button, but since then I have published the updated site to the domain, still no joy.

Any ideas?

Here is my read only link: https://preview.webflow.com/preview/yasirs-first-project-f295b7?utm_medium=preview_link&utm_source=designer&utm_content=yasirs-first-project-f295b7&preview=f7d5d4879100016c7a762e547c79546b&mode=preview

Thank you!

Here is some more info:

What does it mean by ‘certificate has expired’?