No worries,
Go to file manager, should be under system.
Now click on Add source
You should get a box up, in the top part add the above link, in the bottom part give it a name.
Click done and go out, now go to system and then add-ons.
Now go to install from zip file, look for the added link here. Click on it and then just add the repo from here.
Once you add RobinHood project it should just update the one you have.
Hope this helps.