Working together on a game is quite difficult. How do you make sure everyone is on the same page?
You could send zips with assets and code between people, but that is slow, cumbersome, and very error-prone.
This is why Source Control software was invented. With Source Control, you can store the project files on a server, and everyone who wants to work on the project files, can download the project from the server. Once they're done with their changes, they send them back to the server. Then the other people can get those changes from the server again.
There are many different Source Control softwares. Probably the best-known one is git. (Source Control, Version Control, Revision Control all mean essentially the same thing.) Git is very good for working on projects that are all just plain-text code. However, it kind of falls flat when it needs to deal with binary assets, like textures, models, and sounds. Unreal Engine Scenes and Blueprints are also binary files. So if you don't use C++, but only Blueprints, basically your entire project is binary files.
This is why I went looking for a different Version Control Software that can handle this better. At my internship, I used Subversion, which is said to work better with binary assets, but in my experience then, it still wasn't exactly great. Though that might also have been due to the fact that they barely used any of its fancier features there.
Unreal Engine itself recommends using Perforce Helix Core. (Perforce is the company, Helix Core is the VCS, but the term "Perforce" is usually used to refer to the VCS itself, due to historical reasons. Source: https://www.youtube.com/watch?v=jIQEjDiSe0g) So I looked into it, and indeed, it seemed very suitable!
So we requested a computer from the XR Lab to use as server for this project, and I installed the Helix Core Server on it.
It was surprisingly easy to install!
I then downloaded the Helix Core Client application on my laptop, and connected to the server. The setup there took a while, because there was a lot to learn. But in the end, I did it!