Press Windows key + Right Arrow to snap a window to the right half
Press Windows key + Left Arrow to snap a window to the left half
Press Windows key + Up Arrow to maximize the snapped window vertically (optional)
Press Windows key + Down Arrow to restore (optional)
Repeat with another window using the opposite arrow key to fill the other half
Drag a window to the left or right edge until the snap outline appears, then release
Use Snap Assist: after snapping one window, select another window from the pop-up list to fill the remaining space
To split into four: snap one window to a corner by combining Windows key + Left/Right Arrow with Windows key + Up/Down Arrow, then snap the remaining windows into the other corners
To exit split view: drag a snapped window away from the edge or press Windows key + Left/Right Arrow to unsnap