If I read Are free SSL certs supported? – LetsHost Knowledgebase correctly, your hosting provider does not support Let's Encrypt certificates.
Please change hosting provider to one which does not try to swindle you with expensive certificates. Does My Hosting Provider Offer HTTPS? | Certbot provides a list of hosting providers and their Let's Encrypt support.
If changing hosting provider REALLY isn't an option, you might be able to get a certificate anyway using CertSage. See CertSage ACME client (version 1.3.0) - easy webpage interface, optimized for cPanel, no commands to type, root not required for more info