FAB asset pack. Sample map too dark without config folder

I´ve created a bunch of assets that I want to publish on the fab marketplace.

I´ve created a sample room, unsing these assets. Lights are all set to movable since that provides the bet results with Lumen, according to several Tutorials.

Now fab gave me some feedback

“Some partss of the map cannot be seen duue to the darkness. Please test your project without the config folder. Since this project is a asset package is required to work normally without the config folder”

I indeed tried to open it without the config folder and it looks dark. Seems as it has no bounce light in it.

meanwhile, this is how it is supposed to look like:

Any advice how to fix this is highly apprechiated