Using the AxiDraw V3 A3
The Axidraw User Guide has full notes on setting up AxiDraw to use with Inkscape. I've added a condensed version here, but if you have issues it's worth trying out the full instructions first. It also has pictures!
Follow the instructions to install the AxiDraw software and Inkscape 1.2
To check it's installed (re)open Inkscape and look in the 'Extensions' menu: you should see an 'Axidraw Control' option. Click on it and it should open the Axidraw Control menu
Use a micro USB to connect to the machine to your computer. The Axidraw also needs to be externally powered -- there should be one already with the machine, but if not it uses a 9V DC power supply with minumum 1.5A current draw. Please double-check the label on the power supply before plugging it in!
Before you add in the pen, use the 'setup' tab in the Axidraw Control
Screw the pen in 3-6mm above the page, and tape some paper to the desk (see 'understanding the layout' below to figure out how to align)
Now you can use the 'plot' tab in the Axidraw Control menu to print your file! start with something small to check it works
Understanding the Layout
The top left-hand corner of the page you want to draw on should be aligned with the default position of the pen. The 'y-direction' is parallel to the arm that holds the pen; the x-direction is perpendicular to it. Here's a comparison of the output from the plotter vs what was on my computer: