Hi Nev.Pol,
The Twinmotion Materials for Unreal Engine package is not related to the Twinmotion To Unreal plugin.
Please install Twinmotion Content for Unreal Engine Plugin (Beta 4) in Code Plugins - UE Marketplace and Datasmith Twinmotion Importer Plugin (Beta 4) in Code Plugins - UE Marketplace and enable both plugins.
As a reminder, the documentation included in both Marketplace pages explains in detail what plugins you need, how to install, enable, and use the Twinmotion To Unreal workflow.
Hope this helps !
Cheers,
Antoine