Adobe Portfolio SSL error

Hello! I recently created my first Adobe Portfolio, and I've received reports that people encounter a "Your site is not secure" message when trying to load it (althought it works fine on my computer and phone). I did find this article though and realized that my domain name is not correctly mapped to Adobe Portfolio's IP address for some reason -- I have no idea what that means. I don't have a custom domain and don't want to purchase one; I'm good with the .myportfolio.com address and I don't seem to find a way to fix it. Can anyone help me? Cheers!