What are we doing? This is how to add a wildcard Lets Encrypt certificate to your Synology NAS using Cloudflare for DNS authentication.
It is based on the excellent acme.sh. I honestly recommend you read through the docs for acme.sh first. Most of what we are doing is well documented over there. In particular I would look at:
Synology NAS Guide using deployhooks to update the NAS If you find this useful PLEASE consider donating to acme.