In order to be able to control the camera though the Internet outside your home network, you should open up your router settings. (google how to do this for your router). There you will find some settings, including something along the lines of Forwarding or Port Forwarding.
The important thing to note here is the «Port Range» and the «Device» or «IP address». In «Port Range» you should type 80-81. For «Device» you should select your ESP32-CAM device. In some routers you should put the IP address of your ESP32-CAM instead of a device name. Go to www.whatsmyip.org and copy your IP. Use this IP in the App when you are outside your home network.