Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
I think we might need to take a closer look at the settings. Please edit the first post on this ticket and include your WP logins in the designated Sensitive Data section.
It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:
When you enable the .htaccess rules you shared you get an issue saying the SSL certificate is not valid for the www version of your domain.
The easy way is to add an SSL certificate for that www subdomain but since you are using Cloudflare, you will need to add that sub-sub domain to the DNS panel so Cloudflare generates the same SSL certificate for it and you don’t get the current issue.