The Snapping settings dialog is only available to Datum or Off-network asset layers while editing by pressing the Snapping Settings button.

The dialog lists the currently edited layer as well as any other vector layers available in the map view (e.g., shapefiles, File GDB or WFS layers). For each layer, you can control the snapping and define whether to snap to just the vertices of the snapping layer(s) and or its segments or 'edges'