The last time I had a look at the container manager of Synology it was everything but suitable for docker compose. The Zammad stack consists of several containers which required a lot of fiddling. It was anything but updatable etc.
If Synology still doesn’t support proper docker compose, I’d like to suggest (for your own mental peace) to use a virtual machine (on synology if you must) and use docker compose there. It will be much easier and more maintanable that way.