The EFB is a actually a very big project. It requires mapping the following:
EFB
Avionics
ATC
This has to be done for each aircraft individually by…the aircraft builders. They have done it for sim brief and will need to work with asobo to figure out how to do in a way that makes sense. Remember, this is a huuuuge departure from the 2020 world map.
It will likely take a few weeks months before implemention by aircraft builders and debugging by asobo and working title is finished for all aircraft.
However this should have been ready at launch because many of us amateur pilots used the world map in 2020 and have no experience with sim brief.