If you use the public instance you don’t need to set up or host or install anything. You can selfhost it if you want, but the public instance works just fine.
One person goes to the web page and starts a room. The other can join the same room by knowing the name of the room. (It will generate a link when you create a room to make it easy to send to someone so they can join by just clicking the link.)
For anyone wondering why a new law would target reusable bags as well, the phrasing of the old law basically encouraged stores to replace single use plastic bags with reusable plastic bags. Reusable bags use more plastic so they’re sturdier and last longer, but they were treated as single use bags anyways so functionally we were just producing and subsequently wasting more plastic.
I haven’t read this new law but hopefully it encourages or requires actually using paper bags or cardboard boxes or something if you don’t have your own reusable bag. It would be a shame if it just kicks the can down the road again and people buy reusable bags in the checkout aisle that they throw away when they get home instead of keeping in the car.