Here's a quick and easy guide on how to install Adobe Flash Player on Kali Linux.
Visit https://get.adobe.com/flashplayer/ and scroll down to highlight '.tar.gz for other Linux' and hit 'Download Now'. Make sure you download the file to your 'downloads' folder.
We're going to do this the easy way for purposes of simplicity. Simply go to your downloads folder and double click the file to begin extraction. Make a new folder called 'flash' to extract those files into. Once extraction is complete, double click the 'flash' folder to view your files. You should see the following:
While you're in your 'Flash' folder right-click and select 'open in terminal'. Enter the following lines of code:
cp libflashplayer.so /usr/lib/mozilla/plugins/
cp -r usr/* /usr
That's it, you're all set now!