403 Error coming while getting enterprise Users.

Getting below error in /users API 
Request - 
curl -i -X GET "https://api.box.com/2.0/users" \ -H "authorization: Bearer <ACCESS_TOKEN>"

Response -

{ "type": "error", "status": 403, "code": "access_denied_insufficient_permissions", "help_url": "http://developers.box.com/docs/#errors", "message": "Access denied - insufficient permission", "request_id": "qcyqnkhl1oprc6uk" }

What permission or paid account needed to access above API ?