Plugin working or not?

Check your HTML source code (at the end) for the Cache Enabler signature:

E.g.
<!– Cache Enabler by KeyCDN @ 10.11.2015 17:32:29 (html gzip) –>

Please also visit the documentation page for more details: https://www.keycdn.com/support/wordpress-cache-enabler-plugin/

Yes, it working. But where are cache files located?

UP.

I found. /wp-content/cache/cache-enabler