I can install Certbot on my system and try to get a certificate for one of your domains using the manual plugin. If I then tell you to put some challenges in the correct location, I'll get a certificate for your domain. That wouldn't be much different than installing Certbot on a totally unrelated computer (e.g. at home) and then put the challenge files on the correct server using e.g. a cPanel file management system or perhaps using FTP.
2 Likes