If you choose the Online Python Editor, there's nothing to install!
That's it! You are ready to go on to the next page, Test your Connection [2].
Online Python Editor Versions
These Parallax tutorials were originally created with the Online Python Editor versions 1 and 2. Software screencaptures and other illustrations, as well as Python Editor links, may go to v2 ( https://python.microbit.org/v/2 [1].) until all the tutorials can be updated to the Editor v3. All these tutorials are compatible with the updated Python Editor v3; just be aware that the screencaptures may not match yet.
If you are using Windows 7, you will also need to install the mbed serial driver to activate the serial debugging feature. You will need to be logged in to your computer with administrator rights to do this.
Download mbed serial driver [4]
That's it! You are ready to go on to the next page, Test your Connection [2].
Links
[1] https://python.microbit.org/v/2
[2] https://learn.parallax.com/node/1895
[3] https://github.com/mu-editor/mu/releases
[4] http://os.mbed.com/media/downloads/drivers/mbedWinSerial_16466.exe