How to get idle animation from UserId? | Roblox Studio Community | Page 1

I want to load the avatar and the idle animation from a player to another character using their UserId.

Both GetHumanoidDescriptionFromUserId and GetCharacterAppearanceInfoAsync give me the id, but the one you get in marketplace. For example, for the "Rthro Idle" animation I get the animation id "2510235063". But this id can't be used to play the animation. They give the error:
"Failed to load animation with sanitized ID rbxassetid://2510235063: AnimationClip loaded is not valid."
The animation id I need for this one is "10921259953" or "10921258489".

I tried to get the animation id from GetHumanoidDescriptionFromUserId and GetCharacterAppearanceInfoAsync. Looked on google and on other posts from here but didn't find anything.

Here is my script:

local Success, Result = pcall(function()
    return Players:GetHumanoidDescriptionFromUserId(UserId)
end)

if not Success then
    warn("Error while getting avatar description for " .. UserId .. ": " .. Result)
    return
end

local NewHumanoidDescription = Result
DummyToApplyThisTo.Humanoid:ApplyDescription(NewHumanoidDescription)

local Animation = Instance.new("Animation")
Animation.AnimationId = "rbxassetid://" .. NewHumanoidDescription.IdleAnimation

Animation.Parent = Animator
Animator:LoadAnimation(Animation):Play()

#How to get idle animation from UserId?