google sites and github embed not working

aaaah, I am making a unblocked games website and I use the embed link option to add github games, however today I wanted to add more games for my school but every time i put a github link it says something like "this link is invalid it will be turned to text"
but it need it as a full page embed

im trying to add https://sd592g.github.io/zj684od4lfg/