How to set up ip cam in ONVIFER app?

[BetterVision]

I can already access and view the ipcam with ONVIFER, but only locally, not over the internet. The app tells me to forward ports for WAN access, which I did on TP Link TL mr 6400 router (correctly I hope), and to install in the same app, a new ONVIF device by using the WAN access address: xx.x.xxx.xxx:xxxxx, and make sure everything works, but I don't know what name, username and password I should use?