What returns this command sudo iwlist wlan0 scan ?
If you see your wifi listed then do following:
Put your ssid and pw below existing content by editing this file sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
If your Pi still can't connect to the wifi, check if the WiFi ...
I'm learning to do something similar myself. I think the step you are missing here is that you can use a reverse proxy, such as NGINX Proxy Manager, so that you don't need to "type their IP address and port number on the browser", as you mentioned, but instead can access each application as a subdomain, with the proxy directing inbound traffic ...