Questions about opkg

So I installed this long ago and only wanted the basic light footprint. But now since Comcast is putting data caps in specific states, I wanted to monitor bandwidth a little. I installed the vnstat app in LuCI. And then I went to the ;configuration' tab and 'custom feeds', added -
opkg update
opkg install vnstati luci-app-vnstat

I was hoping that I did it correctly but I don't see any changes so I feel like I didn't do it right and I am unsure of where to add that opkg info. I know its gotta be something silly but whenever I search like "how to install opkg" it links to pages that are just like "type opkg and you're good" lol.

My version is OpenWrt 18.06.5 r7897-9d401013fc. I appreciate any info

Are you sure th vnstat process is up and running ?

That's not correct way of installing packages. You need to undo what you did first. If you don't know how to use ssh/CLI, you can install packages from WebUI. Update the list of available packages (may take a bit) and then find packages you want to install in the list.