Access All Client Using WebDAV APIs

Hi,

I want to use WebDAV APIs to access users(clients) from an admin user, I already created an admin, and a client user, but when I try to access one of the files inside the clients folder through cURL, sending the following command (curl -u admin:****** -X GET localhost/remote.php/dav/files/snapTest/Photos/Nut.jpg) , I receive the following message:

<?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
  <s:exception>Sabre\DAV\Exception\NotFound</s:exception>
  <s:message>File not found: Photos in 'snapTest'</s:message>
</d:error>

if I used the same request in the browser but giving the client username and password(while I’m signed in with the client credentials) , I’m able to get the photo.

so how to use WebDAV APIs to access users(clients) from an admin user?

or can I use a master Password that enables me to access all usernames? or there is a another way?

Thanks in advance