As can be seen from the Facebook's official Docs
It says that
To have both a Gameroom and a Facebook Web Game, you should leave your Facebook Web Games URL (https) unchanged. For example, https://friendsmashsample.herokuapp.com/
Otherwise, if you only have a Gameroom title, you should enter https://localhost/ as shown here:
I wanted to know if there is a way to get both of them working instead of hosting WebGL game on my server and putting it's URL?
I have even tried to enable the Simple Web Hosting but the toggle just reverts Back to off upon saving.