Configuration file test failed

[cgiyo]

Hello. This is a question. I follow the instruction, but after alter the nginx.conf with
include rocket-nginx/conf.d/default.conf; I got error like this :

nginx: [emerg] "set" directive is not allowed here in /etc/nginx/rocket-nginx/conf.d/default.conf:19
nginx: configuration file /etc/nginx/nginx.conf test failed

Am I doing wrong? I using WP Rocket version is 3.17.0.2
FYI, I don’t see any configuration file under /etc/nginx/sites-available folder, only in /etc/nginx/sites-enabled folder my configuration file.

Thank you in advance.