Set up?????

I have tried and tried and tried again to install this plug-in with no success.
I have followed all the instructions carefully: is there some step missing?
Or is it no longer operative under WordPress 3.8.1?

Please can you offer some suggestions as this is the only responsive HTML5 Gallery I can find on WordPress.

Thank you

https://ww.wp.xz.cn/plugins/html5-videogallery-plus-player/