SYGNout is installed and running in your menu bar (the icon with signal arcs and an arrow).

Choose Open SYGNout from that icon, or go to http://localhost:8080/. For phones choose Connect a phone…: it shows the address and a QR code. Phones use the https:// address so the camera works.

If another program already uses port 8080 or 8443 the menu says so: choose Ports… to pick others.