The game serves the map as a web page. You can look at it on this PC, or on another device (phone, tablet, another computer).
For another device, it has to be on the same wifi as this PC. Scan the QR code with its camera, or type the link into its browser.
If you pick another device, this tab only shows the QR code and the link. It draws no map, so it costs the game no frame rate.
Anyone who has the link can see your map, so keep it to yourself.
Access from other devices is switched on. Turn it off under DISPLAY > Phone / tablet.
You can change this later: DISPLAY, then Phone / tablet.
Open the map on your other device
Put it on the same wifi as this PC.
Scan this code with its camera, or type the link into its browser.
This tab draws nothing for now. The map starts when the device connects.
Anyone who has this link can see your map. Keep it to yourself.
This opens the map to your network
Right now the map can only be opened on this PC. If you go on, the game also answers other devices on your home network. They need the secret link, but anyone who has it can see where you and everyone else are, so keep it private.
The connection is plain HTTP: use it at home, not on public wifi. If Windows asks about the firewall, choose private networks only. You can switch it off again under DISPLAY.