As I'm writing this small tutorial, I assume you've read my previous one about setting up macOS, so if for any tool I'll use without explanation, look to that other article.
The full version IS NOT MANDATORY, as in the tutorial that follows I installed the smaller version of MacTeX and proceded installing every needed dependency. Installing the complete package is about ~3.5GB of download and ~5GB on disk, the smaller one is just about 80MBs.
Click here to download the complete version or here to download the smaller version.