If you’re not used to writing scripts and other software then I think it might be tough for you to automate this process. We don’t have an existing host-oriented tool and most of the hosting providers who’ve posted here have planned to write some of their own software in order to integrate with their customer flows.
One thing you might want to look at is that control panel environments like Plesk and cPanel now include Let’s Encrypt support, so if you were using control panels of this sort for your customers, they could get Let’s Encrypt support that way.
There are dozens of tools that can get free Let’s Encrypt certificates, but they are mostly aimed at system administrators who are used to configuring each domain individually, or else writing their own scripts for automation purposes. I would suggest asking whoever created the “website builder” tool that you use whether it would be possible to add some kind of Let’s Encrypt support. If not, you might want to think about options like
- changing your software environment to a different environment that supports Let’s Encrypt more automatically
- getting and setting up the certificates more manually, using tools like Certbot or acme.sh
- hiring a developer to set up some scripting or automation for you
I’m sorry that we don’t have a obvious choice for an automatic set of tools for your situation.
One other thing that comes to mind is that the Caddy web server obtains certificates automatically for each domain. I’m not sure whether it would be a reasonable alternative to whichever web server you’re currently using.