Couple of things which I want to highlight,
Maybe the GitHub you are pointing is old, but the concepts remain same.
Communicating with REST API's will not change, you need to use username, secret key, companyName, server details to connect with adobe analytics.
You can find this information in the Admin console-> company information.
You need to understand JSON Objects because, the REST API's accepts JSON object, so you need to know what format the endpoint expects accordingly, you need to build and pass the JSON Object to the API
If you are planning to use JQuery, you can use AJAX request by passing the JSON object as a parameter
Choosing the JQuery or some other technology is based on your comfort level.
Once you get the JSON response, using front end technologies HTML5/css/JS you can showcase on the page based on our requirements.
The important thing is, every REST API hit counts, so it is good to write some scheduler and store the result data in some location and read it from there.