Hey there @Campazzobili! The FAQ’s seem to state that you will have a method of adding the megascans content that you had previously acquired on Quixel to your FAB library through FAB itself.
Any Megascans that you add to your library on Fab during this promotion period, you will be entitled to use under the terms of the Fab Standard License even after the promotion period ends. Please be aware that simply downloading a free Megascan on Fab in 2024 will not grant you this entitlement - you need to use the “Add to library” option.
For additional access and updates, make sure that your Megascans have been added to your Fab library after Fab launches.
It seems you’ll be able to access them through the FAB standard license but only if claimed through the method that will be available. Once the platform releases, we’ll likely also receive more information about the steps to transition.