You can connect your PC or Laptop to the router using a LAN cable or WiFi. Note: Make sure you are connected to the same WiFi router to which your DS220+ is connected. I would still recommend a browser-based setup as it is quick and no additional downloads are required.
Make a note that, there is also an official app called Synology Assistant which will help you set up the NAS. It will take a few seconds and you’ll see the details of your NAS along with Model Number, Mac Address, IP Address, and Status.