I could not find this option, so this might end up as a feature request.
Q: Is there a way to password lock and online file to ensure only those who have the URL and the password can access the files.
If this is not possible, I think it's something adobe should really think about adding as you may need to use interactive options in indesign but with content of a sensitive nature (e.g. company finances) or want to soft share a file with a limited group before allowing global access.