There is a site that can emulate the arcade version of Liquid Kids, it is allowed ?

Here's the site:
https://www.retrogames.cc/arcade-games/liquid-kids-world.html

At your request, we have made it possible to submit with Emulator.
In case of emulator, it would be helpful if you could describe the browser and URL (or MAME,FBA version) in more detail in Description.

So when i post a run i have to describe the emu configs and post the site URL, correct ?

yes.