[Plugin: WordPress HTTPS (SSL)] Can't use on shared server

I know this is an old topic. I have just installed the plugin and I placed my shared host url in the ssl host field. I am using woocommerce, when the user clicks checkout they are taken to a secure page not with the shared host url, it uses https only with the regular domain. I am not greatly technical but with clear instruction I can work my way around wordpress if there is anything I need to change. Don’t want to change the site url in general as the shared host url would be used for the whole site and that is messy.

https://www.ads-software.com/extend/plugins/wordpress-https/