Adobe Flash Player is not pre-installed on Google Nexus 7 (2013). And you can’t find it at Play Store anymore. But that does not mean you can’t use Flash Player on new Nexus 7 with Android 4.3. Yes, you can install it manually with Adobe Flash Player for Android 4.0+ apk. And you need to enable 3rd party apk installation by refer to this guide – How to install 3rd party apk on Nexus 7 (2013)?
Don’t bother to use Google Chrome. It does not support Flash. Use other browsers like Dolphin Browser, Firefox if you want Flash enabled at websites on your Nexus 7 (2013). And be sure to double confirm that Flash is enabled in the browser’s settings. Enjoy…