At the default size, the Populate flows are relatively large.
Create Flow lets you create walkways for the Populate people.
The process of creating a flow is similar to creating a Line spline.
If you don't see any lines, there's a problem with the flow. This typically results from too small an angle between adjacent segments. When this happens, undo (+Z) and make a new flow with larger angles between segments.
Next you'll add an intersection between separate flows.
Intersections need to be a minimum distance from the flow points, which mark the ends of each segment.
A pair of green, crossed arrows appears automatically at the intersection to indicate that the flow direction can change there.
After a brief delay, virtual people appear on the flows. By default, these models use the Textured Skin texture-map set, which is suitable for most purposes. Alternatively, you can display crowd members as stick figures or apply custom textures or high-resolution textures.
In generating the simulation, Populate creates a walking animation for each person.
As the animation plays, the people walk along the flows. When a person encounters the intersection of the two flows, they might turn left or right to walk along the other flow. If this doesn't happen, try increasing the Density value. Then re-simulate and play the animation again.