Website is not Secure in Google Search

Hello! We have been hosting a website for almost a year without issue. We just did a round of changes and all of a sudden the website was down. We checked the Webflow settings and those advised us to add a new CNAME as well as two A Records and voila! the site was live again.

But now when you search, it says the site is not secure. We are not sure how to solve this problem. Any help would be amazing.

Here is my site Read-Only: