https://www.bilibili.com/video/av25441352/
Missing parts:
In the end of Chapter 3, you need to input the code on the image on the floor. Then you can play a shooting game. After finished it, you will clear Chapter 3. In conNEcT01 v1.2, don't worry if you cannot finish it. Just trigger 3 skills, and you will finish it.
Walkthrough (Chinese)
Source: Steam Community (opens in a new tab)