Considering that I've seen no other tutorials on how to build RSDKv5(U) on macOS (and considering that a lot of people just use this tutorial instead), I've decided to take matters into my own hands and futureproof this tutorial so that I never have to worry about it again!
Notes: every time I say to "cd into *specific directory here*", that is your cue to run cd *specific directory here* in the command line.
How to build RSDKv5:
Step 1: Install Xcode and the command tools (the command tools can be installed by running this command: xcode-select --install but only after installing Xcode). If you already have them, move on to step 2.
Step 2: You need to install CMake. If you have Homebrew installed already on your Mac, you can run brew install cmake to install it, but if you don't, you can still install it by using this link (scroll down to where it says "macOS 10.13 or later"). You can then open ~/.zshrc and add `alias cmake = /Applications/CMake.app/Contents/bin/cm