So I tried to look this up but im confused and found multiple people with a similar problem but not mine. I am trying to make a 3d game, with billboarding for all the models because I suck at modeling but im good at drawing. I made the sprite for the playable char, but there’s no option to set it to a billboard or animate on a 3d cube. I have all the sprites and animations in place but not a clue how to get it translated into the game. Sorry im new to developing games so if this is obvious Im sorry
Gotta add 3d Sprite it is an experimental extension. You have to have the gdevelop extension search clicked to show experimental i believe by default it is off.
But remember your character will basically be a piece of paper. Typically you will set up the camera/movement so the character is always facing certain directions so he appears to be 3D while in reality he has no depth.
but then the question is why are using it as 3d game if you arent good in modeling? why not just go 2d or 2d isometric?
You can make 2.5d which is what Square Enix did for its octoravelers series. The world is 3d but the charccters are all sprites. So they always face you cause they are paper. Or think paper mario rpg.
in the 3d engine the only thing that can be animated is 3d model objects and 3d sprites which technically arent 3d since its lacking 1 axis.
When things are modeled in 3d they have skeleton or rig systems to control animation. You want to animate a 3d palm tree you need to rig it up so it can move in the wind.
If you are using sprite sheets for animation that is 2d. And like i said that is where 2.5d games come into play. But it is a very specific look and aeshetic.
I actually already have the sprite set up to go in different angles, but its a horror project that wont be playable to anyone, the reason I need to use sprites is because I can do some cool stuff with the visuals I wouldn’t normally be able to do on a 3d model.
I appreciate the help 
