You can get precompiled binaries and software vocoder plugins for various platforms here: http://pizzanbeer.net/droidstar/
(See below for Mac instructions)
You can buy a hardware dongle that works with droidstar here..
It's called a ThumbDV dongle:
https://nwdigitalradio.com/products/thumbdv™
This is optional (but your audio quality will be better than the software vocoders)
You do not need a software vocoder is you plan to only use M17.
Open up a terminal and copy and paste:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
Verify by running the brew command in the terminal and following any other instructions at https://brew.sh
Open up a terminal and type this command and hit enter:
brew install qt
In addition to these instructions, also refer to any notes at https://github.com/nostar/DroidStar
Make a temp directory and clone the source using the following commands:
mkdir ~/temp
cd ~/temp
git clone https://github.com/nostar/DroidStar.git
cd Droidstar
Now patch the DroidStar.pro file so the vocoder is built in:
sed -i '' 's/#DEFINES += VOCODER_PLUGIN/DEFINES += VOCODER_PLUGIN/' DroidStar.pro
This will create a Makefile using QT:
mkdir build
cd build
qmake ../
This will now hopefully build the software:
make
open ./DroidStar.app
This will open up finder into the build directory you are currently in, so you can move the DroidStar.app to your Applications folder:
open .
cd ~
rm -r -f temp/DroidStar
Simply start with step 3 to download and build from source again.