2 languages separate domains, 1 database

I wonder if anyone can help me here.

I have a website Lightbox Resource which runs in 2 languages. All the data is there and everything works locally just fine.

However, I want the Welsh version to load http://www.bocsgolau.co.uk (language switcher is at the top right). As you can see when you click on the link it takes me to the desired URL but nothing loads. I’m using Polylang to create the 2 languages.

On my hosting I have the folder bocsgolau.co.uk with nothing in it, so it’s obviously going to this folder looking for something and not finding anything. If ANYONE has ANY idea about how to sort this issue out I will be very grateful as it’s been an issue I’ve had for a while.

I basically want it to load the wordpress stuff from lightboxresource.co.uk but just change the url. Is this possible?

Thanks in advance.