Hello,
Welcome to the developer forums! Indeed, it looks like the MagicLeapController component was removed from the v1.4 Unreal sdk. I can confirm internally that this was intentional and update the documentation. In the mean time, if you just need to be able to get the controller pose, you can use the MotionController component that is built in to Unreal-
https://dev.epicgames.com/documentation/en-us/unreal-engine/motion-controller-component-setup-in-unreal-engine?application_version=5.3
The MagicLeapController component inherited from Unreal's MotionController component and basically just added functions for controlling haptic feedback.
If you want to take a look at the MagicLeapController component implementation, the source is included in the UE v1.3 sdk in your MagicLeap folder here-
...\MagicLeap\tools\unreal\plugin\v1.3.0\MagicLeapController\Source\MagicLeapController
Thanks for raising this issue and sorry about the trouble!
Best,
Adam