I'm recreating the chamber seen in the Propulsion Gel demonstration video, and I need to make a trail of the gel on the floor, how do I do it? Is it a separate entity than the gel?

So instead of using a gel dropper and letting the player spread the gel using portals, you want to have the gel in the floor right from the beginning?
Place a few info_paint_sprayer entities above your floor. Change their direction, so they point to your floor. Increase the spread radius, blobs per second, speeds and make it silent. Then use a logic_auto to start them OnMapSpawn and stop them after a few seconds.

I already tried that, but for some reason I couldn't name the info_paint_sprayer, so I couldn't start/stop it. Also, when I put the paint sprayers near the ground the game crashed if I tried to run the map.

Don't upload a BSP just because you are having problems.

Where can I upload then?

And it was an accident, meant to upload vmf...

Upload it as an attachment. The Download system is for map releases.

Sorry, I realize that it was stupid of me, I'm just pretty frustrated with hammer right now.

But heres the vmf of the map, it's not complete but when I tried to add some gel to the floor it crashes on me.

Oh yeah, and gel works fine for every other map I've made.