Recommended and mentioned products
Shinobi is the Open Source CCTV software written in Node.JS. Designed with multiple account system, Streams by WebSocket, and Save to WebM and MP4. Shinobi can record IP Cameras and Local Cameras.
freemium $5.0 / Monthly
Https://shinobi.video/ exists but had bad Docker support last time I checked and is in generally nowhere near as easy to use.
Blue Iris is a high end security monitoring system that lets you view and control the feeds from all the cameras at your home or place of business.
Https://blueirissoftware.com/ is popular on windows but running it on synology under a VM would be generally bad performance wise.