To access the LEGO Speed Champions expansion, please be aware that a new update (approximately 8.2 GB in size) was rolled out for all players. This is a separate download from the ~5 GB pre-load content made available prior to the launch of the expansion. Both updates are required in order for the LEGO Valley location to become accessible in Forza Horizon 4.
Please restart your device then check for updates to start the update process if you don't see these updates automatically.
Forza Horizon 4 LEGO® Speed Champions is included with the Forza Horizon 4 Expansion Bundle and Ultimate Edition. It is also available as a separate expansion purchase. Forza Horizon 4 is required to play.