How to make a bow using FastCast?

I have look at this post but I couldn’t understand how.

script.Parent.FireProjectile.Event:Connect(function(ToolData, tool, firePoint, hitPosition)
	local caster = FastCast.new()
	FastCast.VisualizeCasts = ToolData.DebugMode
	
	local castBehavior = FastCast.newBehavior()
	castBehavior.RaycastParams = castParams
	castBehavior.Acceleration = Vector3.new(0, ToolData.EffectGravity, 0)
	castBehavior.AutoIgnoreContainer = false
	castBehavior.MaxDistance = ToolData.MaxDistance
	castBehavior.CosmeticBulletContainer = projectilesFolder
	castBehavior.CosmeticBulletTemplate = ToolData.Projectile

	castParams.FilterDescendantsInstances = {tool.Parent, projectilesFolder}

	caster.LengthChanged:Connect(function(cast, lastPoint, direction, length, velocity, projectile)
		if projectile then
			local projectileLength = (projectile.Size.Z/2)
			local offset = CFrame.new(0, 0, -(length - projectileLength))
			projectile.CFrame = CFrame.lookAt(lastPoint, lastPoint + direction):ToWorldSpace(offset)
		end
	end)

	caster.RayHit:Connect(function(cast, result, velocity, projectile)
	end)

	local orgin = firePoint.WorldPosition
	local direction = (hitPosition - orgin).Unit
	caster:Fire(orgin, direction, ToolData.BulletSpeed, castBehavior)
end)


What I want:

late response but you can change the direction to be facing more vertically by adding a vector3 and changing the only the y value

local direction = (hitPosition - orgin).Unit + Vector3.new(0,1,0)