If you've placed traffic paths and see them represented by red, orange, yellow, green or blue paths but don't yet see the animated traffic you need to first press play to start the animation. Simply press the play button in the top right of the Beyond CAD interface.

Each traffic animation begins at the start of the path so it may take a while for the scene to be populated by traffic. To speed this up, select 10x (ten times speed) from the play button drop down.