Silva is using instead of the arduino editor. For me the benefits is that I can use external editors, like clion, have autocompletion etc and being able to use a command line tool for compiling and uploading the code.
How to install the PlatformIO tools are described in their documentation here, but for a Mac Homebrew user it might be easiest with:
brew install platformio
To ensure everything is working you should try to compile the source code with
make
If this is the first time running platformio it will also download required tools and libraries defined in the platform.ini file.