Is it required to post the game on liluo.io
Yes, it's the third rule, look: https://itch.io/jam/gdevelop-game-jam-2"Games must be submitted through itch.io for rating as well as Liluo.io (see videos below for instructions)."
Ah, btw does it also need to go in the desc
The rules don't indicate any obligation to put the link, but it's better.
In any case we can know internally if the game has been published on Liluo or not.