[Fnoord]

Ideally you want one reverse proxy software (Apache, Nginx, Caddy - can be anything). For that one, you use Lets Encrypt. The part between the reverse proxy and the rest of the servers (such as Screego in this example) does not need to run over HTTPS unless the link between reverse proxy and server software (ie. Screego) is insecure. If it runs on the same machine, for example both in Docker, then that isn't needed. And, therefore, its beyond the scope of the installation guide. Look for example at a guide on how to set up Nginx s reverse proxy with Lets Encrypt.