Here is how to generate a QRCode so people can access your (or a) wifi network.
Using a QRCode generator that can do plain text or allow the customization or the URL field where it will not put in https:// in front of the text like the QRCode generator in Adobe express does. If the service your using puts in https:// in front of your SSID code it will fail to connect the mobile device to the network.
Adobe Express
WIFI:T:WPA2;S:<$SSID>;P:<$PASSWORD>;;
This allows you more flexibility in a more corporate or creative environment the using the "share" network that comes up on your phone.