As this is part of the NGINX Plus packages, you'll need to ensure you have NGINX Plus installed and configured correctly. You can test to ensure you have NGINX Plus by running nginx -v. This should give you an output similar to the following:
nginx version: nginx/1.11.10 (nginx-plus-r12-p3)
The important part to check is the plus in the naming for nginx-plus-r12-p3.