Addonswow.com is not a valid site to get addons. It's entire collection is just rehosted from other sites and rarely are the addons there up-to-date.
As for getting the library to work, we can't help you if you don't share your entire code and specify what you are doing, what you did, the results you expect, and the results you're getting. Do you have the basics of creating and loading an addon into WoW? Are you saving the file you edited and then reloading the UI when you make changes? Did you read and understand everything on that GitHub page from the author? Did you try getting those examples working first before changing things?
WoW addon development is more involved than just learning a coding language, it takes patience and an understanding of the parts between the lines of code and actually doing something on screen. I uploaded my first addon July 2015, and that was after deciding to learn to make one over the holiday break at the end of 2014. I didn't consider myself "advanced" until years later, and even then, XML still scares me and I refused to use it when making visual stuff. Hell, just digging around the big boy addons confuses the hell out of me. I also refuse to use libraries unless I absolutely have to, like supporting shared media. Learn how to do the simple stuff first before relying on another addon (love the contradictory statement on that Github page, "install this addon so you don't have to rely on an addon" lol).
I self taught myself with wowprogramming.com before it shut down. Since then, all my learning is from digging into other addons, including Blizzard's code extract, and loads of random wiki reads. It also helps that I maintain a personal addon that has grown into thousands of lines of code doing all sorts of random things. It started as just an amalgamation of all the tiny addons I had, some were just a few lines of code, and I was cleaning up my addon list. If it helps for you to read a Lua guide, that's fine, just keep in mind Lua by itself, the barebones language, is tiny. Vast majority of what you need to learn is what Blizzard has implemented. If you want to learn and understand Lua by itself first, you can check out the
official manual online here.