Click on the matching Linux Installer link (32 bit, 64 bit or ARM) to download the installer - save the file to your Downloads folder
From within your Terminal program, cd to the Downloads directory, and untar the package with tar xf arduino*.xz then cd into the arduino-n.n.n folder created:
Run ./install.sh to install the software. I've got an old Ubuntu install so I got warnings, but it did create that desktop icon for me!
Linux doesn't have any drivers to install, assuming you're running a v2.6 kernel or higher, which is almost certainly true. These instructions assume you're running Ubuntu. Each Linux distribution is different, but the instructions should be basic enough to follow for other distros.
You can verify your kernel version by running uname -a in a terminal window, note that this kernel is version 2.6.20
And this one is 3.2.0-23
Some older Linux distributions used to install brltty (braille device) which will conflict with the serial port. You must uninstall brltty if it is installed! Do so by running
sudo apt-get remove brltty or equivalent In a terminal window. If it says it's not installed then thats OK. If you're not running a Debian-derived installation use whatever tool is necessary to verify that you don't have brltty running
Plug in the Circuit Playground, verify that the green LED is lit, and type ls /dev/ttyUSB* into a terminal window, you should see a device file called something like ttyUSB0
If you can't seem to find it, use dmesg | tail right after plugging in the Circuit Playground and look for hints on where it may put the device file. For example here is says Serial Device converter now attached to ttyUSB0
If you see something like this
[ 1900.712000] ftdi_sio 2-10:1.0: FTDI USB Serial Device converter detected
[ 1900.712000] drivers/usb/serial/ftdi_sio.c: Detected FT232BM
[ 1900.712000] usb 2-10: FTDI USB Serial Device converter now attached to ttyUSB0
[ 1901.868000] usb 2-10: usbfs: interface 0 claimed by ftdi_sio while 'brltty' sets config #1
[ 1901.872000] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[ 1901.872000] ftdi_sio 2-10:1.0: device disconnected
That means you have not uninstalled brltty and you should try again.