The using { /Fortnite.com/Devices } Class has a MoveTo function you can use, You can supply the position by passing it from the Prop you want to rotate, and change the rotation by passing a different rotation value, The last parameter is for how long it should take. Here is some suedo code that can help you get started. Look into the spatialmath Module for more guidance.
#Setup Basic Transform Information
set PropTransform = PropToRotate.GetTransform()
set PropPosition = PropTransform.Translation
set PropRotation = PropTransform.Rotation
#90 Degrees in Radians
Radians := 90.0 * (3.14 / 180)
#Need to supply Degrees in Radians to rotate to PropToRotate
PropToRotate.MoveTo(PropToRotate, PropToRotate.ApplyRoll(Radians, 1.0), 4.0)