No, you’re confusing a NAS with an external hard drive (or a hard drive enclosure, which turns an internal hard drive, or a Western Digital shucked hard drive, since their enclosures do not support Macs somehow, into an external drive).

An external hard drive (however you do it) plugs directly into your Mac. A NAS plugs directly into your router. Then it announces itself on the network. You connect to its address (I forget what the command is in Terminal — I have a Mac, too) and then set it up. You set a username/password, then you can connect to it remotely. In Finder you go to Go, then Connect a server, put in the IP address, then it’ll ask for the username/password. Then just favourite it to the left, pin it, whatever. Finder will also remember the IP address. It says it’ll remember it in the Keychain (which is now Apple Passwords, or maybe not) but my MacBook needed the password too, so I’m not sure what TF it was talking about.

Also, Firefox likes my NAS more than Safari does. Not sure what Safari’s major malfunction is, but Firefox is my backup browser.

(Mine’s a Netgear, not a Synology, so maybe a bit different.)