photo won't load to shared album

What do you mean by "won't load when dropped"? Are you trying to import JPEGs to your shared iCloud Photos Library by dropping them into the open Photos window? If you want to import into a Photos Library by dropping photos, make sure, you are having an album selected in Photos where you can import to. Photos will bounce back, if you try to import them while viewing the "Recently Deleted "album, for example. Better drop the photos to be imported into one of your own albums in the "My Albums" section, for example. Or use the command "File > Import" in Photos.

Shared albums are a flat structure. There is no way to structure a shared album with folders. To organize shared albums you would have to create several shared albums, not to dump all photos into the the same shared albums.

macOS Ventura is offering a new method of sharing, somewhat better than shared albums, the shared iCloud Photos Library: How to use iCloud Shared Photo Library - Apple Support

the advantage is, that the photos will be shared at the full resolution, lossless, with all metadata applied, and the adjustments can be reverted. But there is still no way to share the folders and albums. The subscribers will have to recreate the albums in their library.