I fixed the link, it should point to https://github.com/htm-community/nupic-example-code/tree/master/audiostream
I would not suggest using NuPIC today to try and do handwriting recognition applications. You will need to learn a lot about topology and local inhibition and tweak a lot of spatial pooler parameters. Not sure you’d even have much success.
One thing you could try is using the CoordinateEncoder to encode x,y positions and feed them in over time, representing the drawing. But there is no way to get predictions from the CoordinateEncoder yet, so you can’t predict where the pen will be in the future, just how anomalous the current state of the drawing is.