Yes. If your vault is stored in your Dropbox, then select Dropbox.
This will not work as the document provider feature is not implemented in the android app so far. You can not access the unlocked vault via the files app. Only via Cryptomator App. So you can’t select an unlocked vault as destination for your obsidian notes app files.
See here: Using Obsidian with Cryptomator on Android
The desktop app and the mobile apps work differently.
