If your hosting provider can run PHP scripts, one solution might be CertSage ACME client (version 1.2.0) - easy webpage interface, optimized for cPanel, no commands to type, root not required
There are other ways to do it "by hand", if you want, but they aren't always so easy. Most options are command-line tools. Certbot Instructions | Certbot is one example of that. It is intended to be run automatically, but you can run it yourself, and then upload the certificate and key (assuming your provider has some interface to do that). It isn't well documented because so many steps will depend on the specifics of your hosting provider.