Hello Nicola 2 Weeks ago, i did make the below Video, that describes it for a DLC Track. But it should help to do it with any other Track too. If it doesn't, inform me.
If the track is not working with the install you can try to install it manually creating a folder in the ModDev/Locations named "2023_Barcelona". Under "2023_Barcelona" create folders "Assets" and "Catalunha". Now under "Assets" create the following folders - "ANIM" - "GMT" - "MAPS" - MARSHALS" - "MATERIALS". Now go to the Steam\Steamapps\common\rFactor 2\Installed\Locations\2023_Barcelona open the folder 1.15 and you will find several MAS files each one corresponding to the folders you created in the ModDev/Locations/2023_Barcelona. Open each one of them with the "Steam\Steamapps\common\rFactor 2\Support\Tools\MAS2.exe and extract it to the same name folder, that should do the trick. If it doesn't work try to open the SCENE file to check if the structure is the same. Any errors besides that are complicated to explain. Enjoy it.