Transmission error

So, my WordPress site domain comes from Godaddy and is hosted on a Hong Kong server because our target users are mostly from Hong Kong. If I want to improve SEO and start sending backlinks to directory sites, I always get the error message "The URL could not be verified, either the page does not exist or the server is unreachable."

I've read from another platform that someone commented: You get the error because you're using SSL that belongs to someone else. If these directories try to validate your site using https, a warning message will appear warning you that your site may be harmful and that third-party SSL is the reason. My suggestion would be to buy SSL directly from your web host or from a legitimate SSL company. "

But unfortunately I can not guarantee if this is the right way and how I can do that.
Could someone please teach me? Incidentally, my website is a link, hopefully you'll find some pointers with the link. Thank you in advance.