My web server is (include version): include in DSM 7.0
The operating system my web server runs on is (include version):
virtual machine
My hosting provider, if applicable, is:no-ip.com
I can login to a root shell on my machine (yes or no, or I don't know):yes but i can't write @ in it
I'm using a control panel to manage my site (no, or provide the name and version of the control panel):
DSM 7.0
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot): no certbot installed
I think you would be better getting help from a Synology forum. They know your device the best. You are successful at getting the Lets Encrypt certs as we see in crt.sh. It is just a problem to get your device to use them.