It also works with a long tap for very sensitive windows tablets. Pressing the screen for a couple seconds should bring the long tap behaviour of Windows 10, it should show a black bordered square around your finger. Release and you get the marker.
Once you clicked the map, a blue marker will appear, click it and a small popup will appear.
Click Directions and choose directions from/to here. The Directions panel will open, filled with the destination coordinates, just press "Go" to get directions: