Accessing a Synology NAS from Linux

I picked up a Synology DS216j NAS from eBay to use for storage for the rapidly growing home lab. The eventual plan is that as well as my VM backups, it will host the media library, and eventually (when this has all proved itself reasonably bullet-proof) my current DropBox contents. That won’t all fit on the 2x2TB drives that the DS216j came with, and I have a pair of 8TBs on hand, but I wanted to set it up and checked it all worked.