Hello! I exported the maps again from Foundry version 8.8 and it should be compatible now.If you're using The Forge and don't have access to the your data dir, you can upload the webp files using the Tile Browser. Navigate to data/modules, create the folders (1.) like the tutorial says (2.) and upload the images (3.):
EDIT: Looks like The Forge doesn't let you create folders. If you're having this issue, see the reply bellow.
I know that you already have the files set up by now, but if you have trouble doing it using the steps above let me know.
Thanks for your support and sorry for the trouble.
edit: I'll do the same for the other maps that have foundry files next.