Multi User Editing And Git, Github

Hello, We Started a Big Project with My Friend with Unreal Engine 5.4.4 Version We Are Trying to Use Multi User Editing The Problem Is That I Add the File I Got from Unreal Engine Marketplace to the Project It Appears for Me But Not for My Friend We Don’t Know How to Use Git and Github The Videos and Trainings Don’t Seem to Address This Subject If There Is an Expert, It Would Be Good If He Gets Back to Us As Soon As Possible

I Bought the Product for $70 for Testing