Free Google cert is not tied to a trusted root,

[KangJL]

@LesWoolsey

SSL is not accepted

Please read

SSL checker shows "certificate not trusted" warning

When you check your InfinityFree SSL certificate with online SSL checker tools, you might see a warning like this: The certificate is not trusted in all web browsers. You may need to install an Intermediate/chain certificate to link it to a trusted root certificate. This warning sounds scary, but it’s actually not a problem for your website visitors. What this warning means for your site You can safely ignore this warning. Your site will work perfectly fine with HTTPS for virtually all mode…

As for

@LesWoolsey

How can I get a free cert tied to a trusted root

You need to get a custom domain first