You definitely need the ui file (that is the "user interface", or dialog box for the program).  There's not much in the README other than this: "This script lets the user pick a camera/view and a prop/target to follow. The camera will always be facing the direction of the target prop with delay as an adjustable factor. The Offset values creates a distance between the view and the target. Use the Delay value to create a lag between the view and the target."
For installation, just create a folder with all the files in it (mine is named "SmoothCamFollow" and has "main.py', "readme.md", "RELEASENOTES", and "Smooth_Camera_Follow.ui").  Copy this to your iClone 7 OpenPlugin folder (typically C:\Program Files\Reallusion\iClone 7\Bin64\OpenPlugin\).  Next time you run iClone it will show up under "Plug-in" menu.

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I was going to download a viewer but I finally just used my google email account instead.
I'm really surprised they didn't include the installation instructions in the read me file. 
Thanks for your response. I'll give it a go !
It looks pretty cool. 

Yeah ! That was a good installation process. 
It worked just fine.
It wasn't no time before I had the police cruiser out and going. 
I wasn't expecting it to be as smooth as it was. Pretty cool ! 

Thanks !