This site will explain setting up SourceTree, pulling all the assets and code from GitLab stored in a repository and the correct flow for adding code to the repository. It will also cover installing Unity and opening the project. It will explain Unity Cloud Build which gives access to stable builds for all devices allowing almost instant install of the game anywhere without the need for Unity. Which is handy for showing off the game. iOS does require the device which you wish to install onto be a part of the list of accepted devices.
There will be extra reading for building locally for Android, as it requires more software.
A small section on iOS development as it requires you have access to a Mac device for deploying to an iPhone/iPad.
This site also goes over the Coding Standards, File formats and links to the Doxygen Code Documentation for the project.