Hi James! You’re correct that this has been asked before, so you’re in good company. 
Also, the consistent answer is: start at the very beginning of Justin’s Beginner’s course, and do every lesson. Some will seem easy. Some will seem unnecessary. Many offer information you didn’t have before.
You’ll find yourself learning things you don’t think you need. Learn them anyway!!! I was surprised to find that skills I thought did not apply to the music Iike usually do have a place.
You have the app, so you can use it in combination with the website. The lessons track on both platforms. The website offers written information on each lesson, which isn’t available (as I understand) on the app. The app excels for its play-along features.
Here’s a Community thread you might find helpful!