How to wire DotStar LED strip with 6 wires at the start of the strip
Looks like the power and ground (red and black) connections are duplicated. You want to connect the strings in series by plugging the male and female connectors together so that the data lines run all in series, but as the guide points out, you will have a significant voltage drop if you rely on those connections alone or power, so you need to parallel the additional power connections to the supply to maintain brightness with a long chain. If you've only got a single section, you won't need to use the additional connections.