The Tree Of Life is a progressive program, which means that the pre-requisite for subsequent modules is to complete the previous module. For instance, in order to access Module 2, you must first complete Module 1. And in order to access Module 3, you must first complete Module 2.
The reason for this is fairly simple: it is important for students of The Tree Of Life to first learn to walk before they’re expected to run. This measure is instilled for your own personal benefit by laying out a firm foundation before proceeding to more complicated concepts and difficult exercises.