Implementing a date range picker in angular 1x

Question

Everyone, I need your help, I want to implement a date range picker in angular 1x. I installed this one https://github.com/fragaria/angular-daterangepicker the project I'm working with is pretty big, it has a ton of folders and files, look like this and many more folders the project already has bootstrap,momentjs and jquery installed, from the date picker range I installed I dont need those library as I already said the project have them installed, The question is: where should I add the datepicker.css and the angular-datepicker.js files, I tried put the in the root directory and import those files in my index.html but my app crashed. I'm sorry if these questions looks dummy, but this is the fist time im working with angularjs 1x and this is my very first jobs as a developer.