I am using Ubuntu 20.04 ORB SLAM 3 The camera I am using is Built-in iSight

I am very new to ROS and Orb Slam 3 and would like to use my laptop's built-in camera to perform real-time visual mapping using the orb slam 3 package but I don't know where to start or how to do this. I tried searching and looked through the git-hub for Orb slam 3 but I am still confused about the subject. It would be greatly appreciated if anyone can lead me to the right path or post links that would show me how to implement this. Thank You.