CAM use LogonUser to validate the credentials and pass LOGON32_LOGON_INTERACTIVE as the logon type.
The account specified by lpszUsername, must have the necessary account rights. For example, to log on a user with the LOGON32_LOGON_INTERACTIVE flag, the user (or a group to which the user belongs) must have the SE_INTERACTIVE_LOGON_NAME account right. For a list of the account rights that affect the various logon operations, see Account Rights Constants.
The calling process must have the SE_RESTORE_NAME and SE_BACKUP_NAME privileges.
Add the user that you are logged into the server with into the local backup and the service account you are using for CAM:
1.Log on to the computer as a user who has administrative credentials.
2.Click Start, click Run, type Control admintools, and then click OK.
3.Double-click Local Security Policy.
4.In the Local Security Settings dialog box, click Local Policies, double-click User Rights Assignment, and then double-click Backup Files and Directories.
5.In the Backup Files and Directories Properties dialog box, click Add User or Group.
6.In the Select User or Groups dialog box, type the user account that is being used for setup, and then click OK two times.

7 - Restart the server
8 - Then try the install again.