Full official instructions can be found here.
Install MacPorts. Then, in the terminal execute:
port install sbt
Install Homebrew. Then, in the terminal execute:
brew install sbt
Download sbt All platforms (tgz) installation from SBT.
sudo su
cd /opt
mkdir sbt
cd sbt
curl https://dl.bintray.com/sbt/native-packages/sbt/0.13.13/sbt-0.13.13.tgz -o sbt-0.13.13.tgz
Then, execute following
tar zxf sbt-0.13.13.tgz
ln -s sbt-0.13.13 latest
Inside your $HOME make sure to update ~/.profile - by adding following lines
export SBT_HOME=/opt/sbt/latest
export PATH=$PATH:$SBT_HOME/bin
In the terminal execute:
which sbt
You should expect output similar to:
/opt/local/bin/sbt
If you get no output sbt is not installed.