It’s unclear if you’re using iCloud for syncing your vault, or if you’re using another sync service but want to somehow link out to files in iCloud that aren’t directly managed by Obsidian.
If you’re using iCloud for sync, I would think twice about throwing lots of scanned documents into it given this issue:
https://forum.obsidian.md/t/macos-14-sonoma-obsidian-not-loading/