The title Dao De Jing records an order, and the order is not the oldest one known.
In 1973, excavation of a tomb at Mawangdui sealed in the second century BCE recovered two silk manuscripts of the text. Both put the De material first and the Dao material second, which is why the scholarly editions of them are titled the Te-Tao Ching. They are the earliest substantially complete witnesses to the work, and they disagree with the received arrangement on the first thing anyone would notice about it.
In 1993, a tomb at Guodian, dated around 300 BCE, produced bamboo slips carrying roughly a third of the material in three separate bundles, in groupings that match neither arrangement and with no chapter divisions at all. Those slips are the earliest witnesses of any kind, and they show a body of material in circulation before it had settled into the shape either later arrangement gives it.
What follows is genuinely disputed. One position treats the received order as a later editorial decision imposed on an anthology of sayings that had no fixed order to begin with. Another holds that both orders were in circulation early, and that the received one preserves a real grouping rather than inventing it. The Guodian material is too partial to decide between them.
The atlas records the received order because it is the one every citation uses, and records that it is one order among more than one.