Authenticated Origin Pull Update with Bluehost

I’m having to update my Origin pull stuff on my bluehost sites, but support literally did nothing to help me. I’m not even sure I can do it. I have Wordpress installations on Bluehost, and I have the .pem file uploaded, but I don’t know where to add the SSL stuff at. The rep told me .htaccess but that doesn’t seem right? Can I even do it on a shared host, and with a common WordPress install, is it even necessary? Thanks a bunch in advance!

I’m pretty sure it doesn’t apply to your site: