Each mobile number on your account will have a separate Verizon Cloud account associated with it, if it subscribes to the service. To access the content stored in the cloud for a specific device, you have to sign in to the Verizon Cloud website using that device's username and password.
You can't view the cloud content for all of your devices at once, even as the Account Owner. You can only see the cloud content associated with the specific mobile number you sign in under.
Note: Tablets also have a mobile number assigned to them, which you can use to sign in to Verizon Cloud. If you sign in with your tablet number, you'll access the cloud specific to your tablet. If you sign in with your mobile phone number, you can view, sync and back up to your phone's Cloud account. If you don't know your tablet's mobile number, you can find it on the My Devices page in My Verizon.