As stated in Box Securlet prerequisites, Enabling Cloudsoc Securlet in Box Business Settings is required to activate CloudSOC Securlet activation for Box.

To enable use of the Cloudsoc Securlet for Box, please login to Box as a Box admin and follow these steps:

1.  Navigate to the Box Admin Console
2.  Select the cog wheel on the upper right of your Admin Console view
3.  Select Business Settings from the drop-down
4.  Select Apps in the menu bar
5.  Enter "Symantec - Box Securlet" in the Individual Application Controls search bar and click the magnifying glass to display the CloudSoc Securlet entry
6.  Select the "Available" radio button (Note: Most likely the “Disabled” radio button was enabled) 
   1. 

At this point, repeat the Box Securlet activation process in CloudSOC as defined in the Cloudsoc TechNote and confirm you have successfully activated the Securlet in CloudSOC If you do not see this "Individual Application Controls" view using your account to follow the process above, you may not have appropriate access as Box has several levels of administration accounts.