So the first thing you missed is setting the camera to Parallel Projection. You can tell it’s set to Perspective because the blue axis is visible at the bottom.
After setting the camera to Parallel Projection, you need to adjust the window to approximate the aspect ratio of the paper. Are you expecting to print the outer rectangle or is that supposed to represent the paper?
Assuming the latter, erase the rectangle and adjust the model window shape to fit tightly around the model. Use Zoom Extents to fill the space. Tick the box for 1:1 in the export options.
If you just want to print a pattern directly and don’t care about the PDF, go to the Print or Print Preview Window, untick the boxes for Fit to Page and Use Model Extents. Set the Scale to 1 and 1 making sure the units are the same.
