Milonga music is 2/4 time. There are two quarter notes in each measure, each quarter note receives a beat, counted as 1 +, 2 + (1 is the downbeat, 2 is the upbeat, + is the subdivision), which is twice as fast as tango. (See Tango Music and Its Danceability.) How well one dances milonga depends on one's ability to handle its fast rhythm.
There are three ways to do that.
For example, you may step on 1 of the first measure, then on both 1 and 2 of the second measure (slow, quick-quick), or vice versa (quick-quick, slow), or on all downbeats and upbeats (quick-quick, quick-quick).
You may also step on the subdivisions in addition to the downbeats and upbeats: left foot on 1, right foot on +, left foot on 2 (quick-quick, slow); or left foot on 1, right foot on 2, left foot on + (slow, quick-quick); or left foot on 1, right foot on +, left foot on 2, right foot on + (quick-quick, quick-quick).
The third and more advanced way to dance milonga is called milonga traspie. Meaning stumble, traspie refers to the stumble like steps used to reduce the weight change, thus slows down the pace of the dance.
When the foot is blocked by an obstacle, it could either cross over to land on the other side of the obstacle, or rebound back. Similarly, there are two types of milonga traspie.