This is how my .png files look. They all have jagged edges when I look at them in Windows photo viewer and other image viewers:
These are my export settings.
What can I do to get smooth-edged vector graphics?
Depends on what you want to do with the PNG. A standard monitor is 1920 pixels across so try setting your pixel width to 1920 in the export dialogue.
I want to use it in an animation. That seemed to improve it somewhat.