I'm a volunteer with non-profit helping with their website. I'm accustomed to working the frontend, but not the backend. We recently connected the website domain to a new site on Squarespace. Since the domain is now connected to a new site, we can't access the old WordPress site to grab some additional content, etc. Therefore, we want to move the old WP site to an existing sub-domain at the WordPress host.
How can I do this via the cPanel at the WordPress host? (The hosting provider has said they can do it for a fee, but the non-profit would like me to have a go at it first.)